Suppose you have a map array value that is something like this
struct foo {
unsigned iter;
int array[SOME_CONSTANT];
};
You can easily insert this into an array, but you cannot modify the contents of
foo->array[] after the fact. This is because we have no way to verify we won't
go off the end of the array at verification time. This patch provides a start
for this work. We accomplish this by keeping track of a minimum and maximum
value a register could be while we're checking the code. Then at the time we
try to do an access into a MAP_VALUE we verify that the maximum offset into that
region is a valid access into that memory region. So in practice, code such as
this
unsigned index = 0;
if (foo->iter >= SOME_CONSTANT)
foo->iter = index;
else
index = foo->iter++;
foo->array[index] = bar;
would be allowed, as we can verify that index will always be between 0 and
SOME_CONSTANT-1. If you wish to use signed values you'll have to have an extra
check to make sure the index isn't less than 0, or do something like index %=
SOME_CONSTANT.
Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
put_cpu_var takes the percpu data, not the data returned from
get_cpu_var.
This doesn't change the behavior.
Cc: Tejun Heo <tj@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull cgroup fixes from Tejun Heo:
"Three late fixes for cgroup: Two cpuset ones, one trivial and the
other pretty obscure, and a cgroup core fix for a bug which impacts
cgroup v2 namespace users"
* 'for-4.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: fix invalid controller enable rejections with cgroup namespace
cpuset: fix non static symbol warning
cpuset: handle race between CPU hotplug and cpuset_hotplug_work
This prevent future potential pointer leaks when an unprivileged eBPF
program will read a pointer value from its context. Even if
is_valid_access() returns a pointer type, the eBPF verifier replace it
with UNKNOWN_VALUE. The register value that contains a kernel address is
then allowed to leak. Moreover, this fix allows unprivileged eBPF
programs to use functions with (legitimate) pointer arguments.
Not an issue currently since reg_type is only set for PTR_TO_PACKET or
PTR_TO_PACKET_END in XDP and TC programs that can only be loaded as
privileged. For now, the only unprivileged eBPF program allowed is for
socket filtering and all the types from its context are UNKNOWN_VALUE.
However, this fix is important for future unprivileged eBPF programs
which could use pointers in their context.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
some issues. This contains one fix by me and one by Al. I'm sure that
he'll come up with more but for now I tested these patches and they
don't appear to have any negative impact on tracing.
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Merge tag 'trace-v4.8-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracefs fixes from Steven Rostedt:
"Al Viro has been looking at the tracefs code, and has pointed out some
issues. This contains one fix by me and one by Al. I'm sure that
he'll come up with more but for now I tested these patches and they
don't appear to have any negative impact on tracing"
* tag 'trace-v4.8-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
fix memory leaks in tracing_buffers_splice_read()
tracing: Move mutex to protect against resetting of seq data
The iter->seq can be reset outside the protection of the mutex. So can
reading of user data. Move the mutex up to the beginning of the function.
Fixes: d7350c3f45 ("tracing/core: make the read callbacks reentrants")
Cc: stable@vger.kernel.org # 2.6.30+
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull perf fixes from Thomas Gleixner:
"Three fixlets for perf:
- add a missing NULL pointer check in the intel BTS driver
- make BTS an exclusive PMU because BTS can only handle one event at
a time
- ensure that exclusive events are limited to one PMU so that several
exclusive events can be scheduled on different PMU instances"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Limit matching exclusive events to one PMU
perf/x86/intel/bts: Make it an exclusive PMU
perf/x86/intel/bts: Make sure debug store is valid
Pull irq fixes from Thomas Gleixner:
"Three fixes for irq core and irq chip drivers:
- Do not set the irq type if type is NONE. Fixes a boot regression
on various SoCs
- Use the proper cpu for setting up the GIC target list. Discovered
by the cpumask debugging code.
- A rather large fix for the MIPS-GIC so per cpu local interrupts
work again. This was discovered late because the code falls back
to slower timers which use normal device interrupts"
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/mips-gic: Fix local interrupts
irqchip/gicv3: Silence noisy DEBUG_PER_CPU_MAPS warning
genirq: Skip chained interrupt trigger setup if type is IRQ_TYPE_NONE
On the v2 hierarchy, "cgroup.subtree_control" rejects controller
enables if the cgroup has processes in it. The enforcement of this
logic assumes that the cgroup wouldn't have any css_sets associated
with it if there are no tasks in the cgroup, which is no longer true
since a79a908fd2 ("cgroup: introduce cgroup namespaces").
When a cgroup namespace is created, it pins the css_set of the
creating task to use it as the root css_set of the namespace. This
extra reference stays as long as the namespace is around and makes
"cgroup.subtree_control" think that the namespace root cgroup is not
empty even when it is and thus reject controller enables.
Fix it by making cgroup_subtree_control() walk and test emptiness of
each css_set instead of testing whether the list_head is empty.
While at it, update the comment of cgroup_task_count() to indicate
that the returned value may be higher than the number of tasks, which
has always been true due to temporary references and doesn't break
anything.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Cc: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Cc: Aditya Kali <adityakali@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: stable@vger.kernel.org # v4.6+
Fixes: a79a908fd2 ("cgroup: introduce cgroup namespaces")
Link: https://github.com/systemd/systemd/pull/3589#issuecomment-249089541
An "exclusive" PMU is the one that can only have one event scheduled in
at any given time. There may be more than one of such PMUs in a system,
though, like Intel PT and BTS. It should be allowed to have one event
for either of those inside the same context (there may be other constraints
that may prevent this, but those would be hardware-specific). However,
the exclusivity code is written so that only one event from any of the
"exclusive" PMUs is allowed in a context.
Fix this by making the exclusive event filter explicitly match two events'
PMUs.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160920154811.3255-3-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When running as parser interpret BPF_LD | BPF_IMM | BPF_DW
instructions as loading CONST_IMM with the value stored
in imm. The verifier will continue not recognizing those
due to concerns about search space/program complexity
increase.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Advanced JIT compilers and translators may want to use
eBPF verifier as a base for parsers or to perform custom
checks and validations.
Add ability for external users to invoke the verifier
and provide callbacks to be invoked for every intruction
checked. For now only add most basic callback for
per-instruction pre-interpretation checks is added. More
advanced users may also like to have per-instruction post
callback and state comparison callback.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Move verifier's internal structures to a header file and
prefix their names with bpf_ to avoid potential namespace
conflicts. Those structures will soon be used by external
analyzers.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Storing state in reserved fields of instructions makes
it impossible to run verifier on programs already
marked as read-only. Allocate and use an array of
per-instruction state instead.
While touching the error path rename and move existing
jump target.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This work implements direct packet access for helpers and direct packet
write in a similar fashion as already available for XDP types via commits
4acf6c0b84 ("bpf: enable direct packet data write for xdp progs") and
6841de8b0d ("bpf: allow helpers access the packet directly"), and as a
complementary feature to the already available direct packet read for tc
(cls/act) programs.
For enabling this, we need to introduce two helpers, bpf_skb_pull_data()
and bpf_csum_update(). The first is generally needed for both, read and
write, because they would otherwise only be limited to the current linear
skb head. Usually, when the data_end test fails, programs just bail out,
or, in the direct read case, use bpf_skb_load_bytes() as an alternative
to overcome this limitation. If such data sits in non-linear parts, we
can just pull them in once with the new helper, retest and eventually
access them.
At the same time, this also makes sure the skb is uncloned, which is, of
course, a necessary condition for direct write. As this needs to be an
invariant for the write part only, the verifier detects writes and adds
a prologue that is calling bpf_skb_pull_data() to effectively unclone the
skb from the very beginning in case it is indeed cloned. The heuristic
makes use of a similar trick that was done in 233577a220 ("net: filter:
constify detection of pkt_type_offset"). This comes at zero cost for other
programs that do not use the direct write feature. Should a program use
this feature only sparsely and has read access for the most parts with,
for example, drop return codes, then such write action can be delegated
to a tail called program for mitigating this cost of potential uncloning
to a late point in time where it would have been paid similarly with the
bpf_skb_store_bytes() as well. Advantage of direct write is that the
writes are inlined whereas the helper cannot make any length assumptions
and thus needs to generate a call to memcpy() also for small sizes, as well
as cost of helper call itself with sanity checks are avoided. Plus, when
direct read is already used, we don't need to cache or perform rechecks
on the data boundaries (due to verifier invalidating previous checks for
helpers that change skb->data), so more complex programs using rewrites
can benefit from switching to direct read plus write.
For direct packet access to helpers, we save the otherwise needed copy into
a temp struct sitting on stack memory when use-case allows. Both facilities
are enabled via may_access_direct_pkt_data() in verifier. For now, we limit
this to map helpers and csum_diff, and can successively enable other helpers
where we find it makes sense. Helpers that definitely cannot be allowed for
this are those part of bpf_helper_changes_skb_data() since they can change
underlying data, and those that write into memory as this could happen for
packet typed args when still cloned. bpf_csum_update() helper accommodates
for the fact that we need to fixup checksum_complete when using direct write
instead of bpf_skb_store_bytes(), meaning the programs can use available
helpers like bpf_csum_diff(), and implement csum_add(), csum_sub(),
csum_block_add(), csum_block_sub() equivalents in eBPF together with the
new helper. A usage example will be provided for iproute2's examples/bpf/
directory.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Current contract for the following two helper argument types is:
* ARG_CONST_STACK_SIZE: passed argument pair must be (ptr, >0).
* ARG_CONST_STACK_SIZE_OR_ZERO: passed argument pair can be either
(NULL, 0) or (ptr, >0).
With 6841de8b0d ("bpf: allow helpers access the packet directly"), we can
pass also raw packet data to helpers, so depending on the argument type
being PTR_TO_PACKET, we now either assert memory via check_packet_access()
or check_stack_boundary(). As a result, the tests in check_packet_access()
currently allow more than intended with regards to reg->imm.
Back in 969bf05eb3 ("bpf: direct packet access"), check_packet_access()
was fine to ignore size argument since in check_mem_access() size was
bpf_size_to_bytes() derived and prior to the call to check_packet_access()
guaranteed to be larger than zero.
However, for the above two argument types, it currently means, we can have
a <= 0 size and thus breaking current guarantees for helpers. Enforce a
check for size <= 0 and bail out if so.
check_stack_boundary() doesn't have such an issue since it already tests
for access_size <= 0 and bails out, resp. access_size == 0 in case of NULL
pointer passed when allowed.
Fixes: 6841de8b0d ("bpf: allow helpers access the packet directly")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
When a socket is cloned, the associated sock_cgroup_data is duplicated
but not its reference on the cgroup. As a result, the cgroup reference
count will underflow when both sockets are destroyed later on.
Fixes: bd1060a1d6 ("sock, cgroup: add sock->sk_cgroup")
Link: http://lkml.kernel.org/r/20160914194846.11153-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: <stable@vger.kernel.org> [4.5+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is no point in trying to configure the trigger of a chained
interrupt if no trigger information has been configured. At best
this is ignored, and at the worse this confuses the underlying
irqchip (which is likely not to handle such a thing), and
unnecessarily alarms the user.
Only apply the configuration if type is not IRQ_TYPE_NONE.
Fixes: 1e12c4a939 ("genirq: Correctly configure the trigger on chained interrupts")
Reported-and-tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/CAMuHMdVW1eTn20=EtYcJ8hkVwohaSuH_yQXrY2MGBEvZ8fpFOg@mail.gmail.com
Link: http://lkml.kernel.org/r/1474274967-15984-1-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fixes the following sparse warning:
kernel/cpuset.c:2088:6: warning:
symbol 'cpuset_fork' was not declared. Should it be static?
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull scheduler fix from Ingo Molnar:
"A try_to_wake_up() memory ordering race fix causing a busy-loop in
ttwu()"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Fix a race between try_to_wake_up() and a woken up task
Pull perf fixes from Ingo Molnar:
"This contains:
- a set of fixes found by directed-random perf fuzzing efforts by
Vince Weaver, Alexander Shishkin and Peter Zijlstra
- a cqm driver crash fix
- an AMD uncore driver use after free fix"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel: Fix PEBSv3 record drain
perf/x86/intel/bts: Kill a silly warning
perf/x86/intel/bts: Fix BTS PMI detection
perf/x86/intel/bts: Fix confused ordering of PMU callbacks
perf/core: Fix aux_mmap_count vs aux_refcount order
perf/core: Fix a race between mmap_close() and set_output() of AUX events
perf/x86/amd/uncore: Prevent use after free
perf/x86/intel/cqm: Check cqm/mbm enabled state in event init
perf/core: Remove WARN from perf_event_read()
A discrepancy between cpu_online_mask and cpuset's effective_cpus
mask is inevitable during hotplug since cpuset defers updating of
effective_cpus mask using a workqueue, during which time nothing
prevents the system from more hotplug operations. For that reason
guarantee_online_cpus() walks up the cpuset hierarchy until it finds
an intersection under the assumption that top cpuset's effective_cpus
mask intersects with cpu_online_mask even with such a race occurring.
However a sequence of CPU hotplugs can open a time window, during which
none of the effective CPUs in the top cpuset intersect with
cpu_online_mask.
For example when there are 4 possible CPUs 0-3 and only CPU0 is online:
======================== ===========================
cpu_online_mask top_cpuset.effective_cpus
======================== ===========================
echo 1 > cpu2/online.
CPU hotplug notifier woke up hotplug work but not yet scheduled.
[0,2] [0]
echo 0 > cpu0/online.
The workqueue is still runnable.
[2] [0]
======================== ===========================
Now there is no intersection between cpu_online_mask and
top_cpuset.effective_cpus. Thus invoking sys_sched_setaffinity() at
this moment can cause following:
Unable to handle kernel NULL pointer dereference at virtual address 000000d0
------------[ cut here ]------------
Kernel BUG at ffffffc0001389b0 [verbose debug info unavailable]
Internal error: Oops - BUG: 96000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 2 PID: 1420 Comm: taskset Tainted: G W 4.4.8+ #98
task: ffffffc06a5c4880 ti: ffffffc06e124000 task.ti: ffffffc06e124000
PC is at guarantee_online_cpus+0x2c/0x58
LR is at cpuset_cpus_allowed+0x4c/0x6c
<snip>
Process taskset (pid: 1420, stack limit = 0xffffffc06e124020)
Call trace:
[<ffffffc0001389b0>] guarantee_online_cpus+0x2c/0x58
[<ffffffc00013b208>] cpuset_cpus_allowed+0x4c/0x6c
[<ffffffc0000d61f0>] sched_setaffinity+0xc0/0x1ac
[<ffffffc0000d6374>] SyS_sched_setaffinity+0x98/0xac
[<ffffffc000085cb0>] el0_svc_naked+0x24/0x28
The top cpuset's effective_cpus are guaranteed to be identical to
cpu_online_mask eventually. Hence fall back to cpu_online_mask when
there is no intersection between top cpuset's effective_cpus and
cpu_online_mask.
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: cgroups@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: <stable@vger.kernel.org> # 3.17+
Signed-off-by: Tejun Heo <tj@kernel.org>
Conflicts:
drivers/net/ethernet/mediatek/mtk_eth_soc.c
drivers/net/ethernet/qlogic/qed/qed_dcbx.c
drivers/net/phy/Kconfig
All conflicts were cases of overlapping commits.
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull libnvdimm fixes from Dan Williams:
"nvdimm fixes for v4.8, two of them are tagged for -stable:
- Fix devm_memremap_pages() to use track_pfn_insert(). Otherwise,
DAX pmd mappings end up with an uncached pgprot, and unusable
performance for the device-dax interface. The device-dax interface
appeared in 4.7 so this is tagged for -stable.
- Fix a couple VM_BUG_ON() checks in the show_smaps() path to
understand DAX pmd entries. This fix is tagged for -stable.
- Fix a mis-merge of the nfit machine-check handler to flip the
polarity of an if() to match the final version of the patch that
Vishal sent for 4.8-rc1. Without this the nfit machine check
handler never detects / inserts new 'badblocks' entries which
applications use to identify lost portions of files.
- For test purposes, fix the nvdimm_clear_poison() path to operate on
legacy / simulated nvdimm memory ranges. Without this fix a test
can set badblocks, but never clear them on these ranges.
- Fix the range checking done by dax_dev_pmd_fault(). This is not
tagged for -stable since this problem is mitigated by specifying
aligned resources at device-dax setup time.
These patches have appeared in a next release over the past week. The
recent rebase you can see in the timestamps was to drop an invalid fix
as identified by the updated device-dax unit tests [1]. The -mm
touches have an ack from Andrew"
[1]: "[ndctl PATCH 0/3] device-dax test for recent kernel bugs"
https://lists.01.org/pipermail/linux-nvdimm/2016-September/006855.html
* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
libnvdimm: allow legacy (e820) pmem region to clear bad blocks
nfit, mce: Fix SPA matching logic in MCE handler
mm: fix cache mode of dax pmd mappings
mm: fix show_smap() for zone_device-pmd ranges
dax: fix mapping size check
The order of accesses to ring buffer's aux_mmap_count and aux_refcount
has to be preserved across the users, namely perf_mmap_close() and
perf_aux_output_begin(), otherwise the inversion can result in the latter
holding the last reference to the aux buffer and subsequently free'ing
it in atomic context, triggering a warning.
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 257 at kernel/events/ring_buffer.c:541 __rb_free_aux+0x11a/0x130
> CPU: 0 PID: 257 Comm: stopbug Not tainted 4.8.0-rc1+ #2596
> Call Trace:
> [<ffffffff810f3e0b>] __warn+0xcb/0xf0
> [<ffffffff810f3f3d>] warn_slowpath_null+0x1d/0x20
> [<ffffffff8121182a>] __rb_free_aux+0x11a/0x130
> [<ffffffff812127a8>] rb_free_aux+0x18/0x20
> [<ffffffff81212913>] perf_aux_output_begin+0x163/0x1e0
> [<ffffffff8100c33a>] bts_event_start+0x3a/0xd0
> [<ffffffff8100c42d>] bts_event_add+0x5d/0x80
> [<ffffffff81203646>] event_sched_in.isra.104+0xf6/0x2f0
> [<ffffffff8120652e>] group_sched_in+0x6e/0x190
> [<ffffffff8120694e>] ctx_sched_in+0x2fe/0x5f0
> [<ffffffff81206ca0>] perf_event_sched_in+0x60/0x80
> [<ffffffff81206d1b>] ctx_resched+0x5b/0x90
> [<ffffffff81207281>] __perf_event_enable+0x1e1/0x240
> [<ffffffff81200639>] event_function+0xa9/0x180
> [<ffffffff81202000>] ? perf_cgroup_attach+0x70/0x70
> [<ffffffff8120203f>] remote_function+0x3f/0x50
> [<ffffffff811971f3>] flush_smp_call_function_queue+0x83/0x150
> [<ffffffff81197bd3>] generic_smp_call_function_single_interrupt+0x13/0x60
> [<ffffffff810a6477>] smp_call_function_single_interrupt+0x27/0x40
> [<ffffffff81a26ea9>] call_function_single_interrupt+0x89/0x90
> [<ffffffff81120056>] finish_task_switch+0xa6/0x210
> [<ffffffff81120017>] ? finish_task_switch+0x67/0x210
> [<ffffffff81a1e83d>] __schedule+0x3dd/0xb50
> [<ffffffff81a1efe5>] schedule+0x35/0x80
> [<ffffffff81128031>] sys_sched_yield+0x61/0x70
> [<ffffffff81a25be5>] entry_SYSCALL_64_fastpath+0x18/0xa8
> ---[ end trace 6235f556f5ea83a9 ]---
This patch puts the checks in perf_aux_output_begin() in the same order
as that of perf_mmap_close().
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160906132353.19887-3-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the mmap_close() path we need to stop all the AUX events that are
writing data to the AUX area that we are unmapping, before we can
safely free the pages. To determine if an event needs to be stopped,
we're comparing its ->rb against the one that's getting unmapped.
However, a SET_OUTPUT ioctl may turn up inside an AUX transaction
and swizzle event::rb to some other ring buffer, but the transaction
will keep writing data to the old ring buffer until the event gets
scheduled out. At this point, mmap_close() will skip over such an
event and will proceed to free the AUX area, while it's still being
used by this event, which will set off a warning in the mmap_close()
path and cause a memory corruption.
To avoid this, always stop an AUX event before its ->rb is updated;
this will release the (potentially) last reference on the AUX area
of the buffer. If the event gets restarted, its new ring buffer will
be used. If another SET_OUTPUT comes and switches it back to the
old ring buffer that's getting unmapped, it's also fine: this
ring buffer's aux_mmap_count will be zero and AUX transactions won't
start any more.
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160906132353.19887-2-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions
to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros
that are used today. Motivation for this is to hide all the register handling
and all necessary casts from the user, so that it is done automatically in the
background when adding a BPF_CALL_<n>() call.
This makes current helpers easier to review, eases to write future helpers,
avoids getting the casting mess wrong, and allows for extending all helpers at
once (f.e. build time checks, etc). It also helps detecting more easily in
code reviews that unused registers are not instrumented in the code by accident,
breaking compatibility with existing programs.
BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some
fundamental differences, for example, for generating the actual helper function
that carries all u64 regs, we need to fill unused regs, so that we always end up
with 5 u64 regs as an argument.
I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and
they look all as expected. No sparse issue spotted. We let this also sit for a
few days with Fengguang's kbuild test robot, and there were no issues seen. On
s390, it barked on the "uses dynamic stack allocation" notice, which is an old
one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion
to the call wrapper, just telling that the perf raw record/frag sits on stack
(gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests
and they were fine as well. All eBPF helpers are now converted to use these
macros, getting rid of a good chunk of all the raw castings.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add BPF_SIZEOF() and BPF_FIELD_SIZEOF() macros to improve the code a bit
which otherwise often result in overly long bytes_to_bpf_size(sizeof())
and bytes_to_bpf_size(FIELD_SIZEOF()) lines. So place them into a macro
helper instead. Moreover, we currently have a BUILD_BUG_ON(BPF_FIELD_SIZEOF())
check in convert_bpf_extensions(), but we should rather make that generic
as well and add a BUILD_BUG_ON() test in all BPF_SIZEOF()/BPF_FIELD_SIZEOF()
users to detect any rewriter size issues at compile time. Note, there are
currently none, but we want to assert that it stays this way.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Some minor misc cleanups, f.e. use sizeof(__u32) instead of hardcoding
and in __bpf_skb_max_len(), I missed that we always have skb->dev valid
anyway, so we can drop the unneeded test for dev; also few more other
misc bits addressed here.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
track_pfn_insert() in vmf_insert_pfn_pmd() is marking dax mappings as
uncacheable rendering them impractical for application usage. DAX-pte
mappings are cached and the goal of establishing DAX-pmd mappings is to
attain more performance, not dramatically less (3 orders of magnitude).
track_pfn_insert() relies on a previous call to reserve_memtype() to
establish the expected page_cache_mode for the range. While memremap()
arranges for reserve_memtype() to be called, devm_memremap_pages() does
not. So, teach track_pfn_insert() and untrack_pfn() how to handle
tracking without a vma, and arrange for devm_memremap_pages() to
establish the write-back-cache reservation in the memtype tree.
Cc: <stable@vger.kernel.org>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Toshi Kani <toshi.kani@hpe.com>
Reported-by: Kai Zhang <kai.ka.zhang@oracle.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
LLVM can generate code that tests for direct packet access via
skb->data/data_end in a way that currently gets rejected by the
verifier, example:
[...]
7: (61) r3 = *(u32 *)(r6 +80)
8: (61) r9 = *(u32 *)(r6 +76)
9: (bf) r2 = r9
10: (07) r2 += 54
11: (3d) if r3 >= r2 goto pc+12
R1=inv R2=pkt(id=0,off=54,r=0) R3=pkt_end R4=inv R6=ctx
R9=pkt(id=0,off=0,r=0) R10=fp
12: (18) r4 = 0xffffff7a
14: (05) goto pc+430
[...]
from 11 to 24: R1=inv R2=pkt(id=0,off=54,r=0) R3=pkt_end R4=inv
R6=ctx R9=pkt(id=0,off=0,r=0) R10=fp
24: (7b) *(u64 *)(r10 -40) = r1
25: (b7) r1 = 0
26: (63) *(u32 *)(r6 +56) = r1
27: (b7) r2 = 40
28: (71) r8 = *(u8 *)(r9 +20)
invalid access to packet, off=20 size=1, R9(id=0,off=0,r=0)
The reason why this gets rejected despite a proper test is that we
currently call find_good_pkt_pointers() only in case where we detect
tests like rX > pkt_end, where rX is of type pkt(id=Y,off=Z,r=0) and
derived, for example, from a register of type pkt(id=Y,off=0,r=0)
pointing to skb->data. find_good_pkt_pointers() then fills the range
in the current branch to pkt(id=Y,off=0,r=Z) on success.
For above case, we need to extend that to recognize pkt_end >= rX
pattern and mark the other branch that is taken on success with the
appropriate pkt(id=Y,off=0,r=Z) type via find_good_pkt_pointers().
Since eBPF operates on BPF_JGT (>) and BPF_JGE (>=), these are the
only two practical options to test for from what LLVM could have
generated, since there's no such thing as BPF_JLT (<) or BPF_JLE (<=)
that we would need to take into account as well.
After the fix:
[...]
7: (61) r3 = *(u32 *)(r6 +80)
8: (61) r9 = *(u32 *)(r6 +76)
9: (bf) r2 = r9
10: (07) r2 += 54
11: (3d) if r3 >= r2 goto pc+12
R1=inv R2=pkt(id=0,off=54,r=0) R3=pkt_end R4=inv R6=ctx
R9=pkt(id=0,off=0,r=0) R10=fp
12: (18) r4 = 0xffffff7a
14: (05) goto pc+430
[...]
from 11 to 24: R1=inv R2=pkt(id=0,off=54,r=54) R3=pkt_end R4=inv
R6=ctx R9=pkt(id=0,off=0,r=54) R10=fp
24: (7b) *(u64 *)(r10 -40) = r1
25: (b7) r1 = 0
26: (63) *(u32 *)(r6 +56) = r1
27: (b7) r2 = 40
28: (71) r8 = *(u8 *)(r9 +20)
29: (bf) r1 = r8
30: (25) if r8 > 0x3c goto pc+47
R1=inv56 R2=imm40 R3=pkt_end R4=inv R6=ctx R8=inv56
R9=pkt(id=0,off=0,r=54) R10=fp
31: (b7) r1 = 1
[...]
Verifier test cases are also added in this work, one that demonstrates
the mentioned example here and one that tries a bad packet access for
the current/fall-through branch (the one with types pkt(id=X,off=Y,r=0),
pkt(id=X,off=0,r=0)), then a case with good and bad accesses, and two
with both test variants (>, >=).
Fixes: 969bf05eb3 ("bpf: direct packet access")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The newly added bpf_overflow_handler function is only built of both
CONFIG_EVENT_TRACING and CONFIG_BPF_SYSCALL are enabled, but the caller
only checks the latter:
kernel/events/core.c: In function 'perf_event_alloc':
kernel/events/core.c:9106:27: error: 'bpf_overflow_handler' undeclared (first use in this function)
This changes the caller so we also skip this call if CONFIG_EVENT_TRACING
is disabled entirely.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: aa6a5f3cb2 ("perf, bpf: add perf events core support for BPF_PROG_TYPE_PERF_EVENT programs")
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
of_clk_init() ends up calling into pm_qos_update_request() very early
during boot where irq is expected to stay disabled.
pm_qos_update_request() uses cancel_delayed_work_sync() which
correctly assumes that irq is enabled on invocation and
unconditionally disables and re-enables it.
Gate cancel_delayed_work_sync() invocation with kevented_up() to avoid
enabling irq unexpectedly during early boot.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Qiao Zhou <qiaozhou@asrmicro.com>
Link: http://lkml.kernel.org/r/d2501c4c-8e7b-bea3-1b01-000b36b5dfe9@asrmicro.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The origin of the issue I've seen is related to
a missing memory barrier between check for task->state and
the check for task->on_rq.
The task being woken up is already awake from a schedule()
and is doing the following:
do {
schedule()
set_current_state(TASK_(UN)INTERRUPTIBLE);
} while (!cond);
The waker, actually gets stuck doing the following in
try_to_wake_up():
while (p->on_cpu)
cpu_relax();
Analysis:
The instance I've seen involves the following race:
CPU1 CPU2
while () {
if (cond)
break;
do {
schedule();
set_current_state(TASK_UN..)
} while (!cond);
wakeup_routine()
spin_lock_irqsave(wait_lock)
raw_spin_lock_irqsave(wait_lock) wake_up_process()
} try_to_wake_up()
set_current_state(TASK_RUNNING); ..
list_del(&waiter.list);
CPU2 wakes up CPU1, but before it can get the wait_lock and set
current state to TASK_RUNNING the following occurs:
CPU3
wakeup_routine()
raw_spin_lock_irqsave(wait_lock)
if (!list_empty)
wake_up_process()
try_to_wake_up()
raw_spin_lock_irqsave(p->pi_lock)
..
if (p->on_rq && ttwu_wakeup())
..
while (p->on_cpu)
cpu_relax()
..
CPU3 tries to wake up the task on CPU1 again since it finds
it on the wait_queue, CPU1 is spinning on wait_lock, but immediately
after CPU2, CPU3 got it.
CPU3 checks the state of p on CPU1, it is TASK_UNINTERRUPTIBLE and
the task is spinning on the wait_lock. Interestingly since p->on_rq
is checked under pi_lock, I've noticed that try_to_wake_up() finds
p->on_rq to be 0. This was the most confusing bit of the analysis,
but p->on_rq is changed under runqueue lock, rq_lock, the p->on_rq
check is not reliable without this fix IMHO. The race is visible
(based on the analysis) only when ttwu_queue() does a remote wakeup
via ttwu_queue_remote. In which case the p->on_rq change is not
done uder the pi_lock.
The result is that after a while the entire system locks up on
the raw_spin_irqlock_save(wait_lock) and the holder spins infintely
Reproduction of the issue:
The issue can be reproduced after a long run on my system with 80
threads and having to tweak available memory to very low and running
memory stress-ng mmapfork test. It usually takes a long time to
reproduce. I am trying to work on a test case that can reproduce
the issue faster, but thats work in progress. I am still testing the
changes on my still in a loop and the tests seem OK thus far.
Big thanks to Benjamin and Nick for helping debug this as well.
Ben helped catch the missing barrier, Nick caught every missing
bit in my theory.
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
[ Updated comment to clarify matching barriers. Many
architectures do not have a full barrier in switch_to()
so that cannot be relied upon. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicholas Piggin <nicholas.piggin@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/e02cce7b-d9ca-1ad0-7a61-ea97c7582b37@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This effectively reverts commit:
71e7bc2bab ("perf/core: Check return value of the perf_event_read() IPI")
... and puts in a comment explaining why we ignore the return value.
Reported-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David Carrillo-Cisneros <davidcc@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 71e7bc2bab ("perf/core: Check return value of the perf_event_read() IPI")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull timer fixes from Thomas Gleixner:
"Two fixlet from the timers departement:
- A fix for scheduler stalls in the tick idle code affecting
NOHZ_FULL kernels
- A trivial compile fix"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tick/nohz: Fix softlockup on scheduler stalls in kvm guest
clocksource/drivers/atmel-pit: Fix compilation error
Allow attaching BPF_PROG_TYPE_PERF_EVENT programs to sw and hw perf events
via overflow_handler mechanism.
When program is attached the overflow_handlers become stacked.
The program acts as a filter.
Returning zero from the program means that the normal perf_event_output handler
will not be called and sampling event won't be stored in the ring buffer.
The overflow_handler_context==NULL is an additional safety check
to make sure programs are not attached to hw breakpoints and watchdog
in case other checks (that prevent that now anyway) get accidentally
relaxed in the future.
The program refcnt is incremented in case perf_events are inhereted
when target task is forked.
Similar to kprobe and tracepoint programs there is no ioctl to
detach the program or swap already attached program. The user space
expected to close(perf_event_fd) like it does right now for kprobe+bpf.
That restriction simplifies the code quite a bit.
The invocation of overflow_handler in __perf_event_overflow() is now
done via READ_ONCE, since that pointer can be replaced when the program
is attached while perf_event itself could have been active already.
There is no need to do similar treatment for event->prog, since it's
assigned only once before it's accessed.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use
preallocated hash maps, since doing memory allocation
in overflow_handler can crash depending on where nmi got triggered.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Introduce BPF_PROG_TYPE_PERF_EVENT programs that can be attached to
HW and SW perf events (PERF_TYPE_HARDWARE and PERF_TYPE_SOFTWARE
correspondingly in uapi/linux/perf_event.h)
The program visible context meta structure is
struct bpf_perf_event_data {
struct pt_regs regs;
__u64 sample_period;
};
which is accessible directly from the program:
int bpf_prog(struct bpf_perf_event_data *ctx)
{
... ctx->sample_period ...
... ctx->regs.ip ...
}
The bpf verifier rewrites the accesses into kernel internal
struct bpf_perf_event_data_kern which allows changing
struct perf_sample_data without affecting bpf programs.
New fields can be added to the end of struct bpf_perf_event_data
in the future.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The verifier supported only 4-byte metafields in
struct __sk_buff and struct xdp_md. The metafields in upcoming
struct bpf_perf_event are 8-byte to match register width in struct pt_regs.
Teach verifier to recognize 8-byte metafield access.
The patch doesn't affect safety of sockets and xdp programs.
They check for 4-byte only ctx access before these conditions are hit.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
tick_nohz_start_idle() is prevented to be called if the idle tick can't
be stopped since commit 1f3b0f8243 ("tick/nohz: Optimize nohz idle
enter"). As a result, after suspend/resume the host machine, full dynticks
kvm guest will softlockup:
NMI watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [swapper/0:0]
Call Trace:
default_idle+0x31/0x1a0
arch_cpu_idle+0xf/0x20
default_idle_call+0x2a/0x50
cpu_startup_entry+0x39b/0x4d0
rest_init+0x138/0x140
? rest_init+0x5/0x140
start_kernel+0x4c1/0x4ce
? set_init_arg+0x55/0x55
? early_idt_handler_array+0x120/0x120
x86_64_start_reservations+0x24/0x26
x86_64_start_kernel+0x142/0x14f
In addition, cat /proc/stat | grep cpu in guest or host:
cpu 398 16 5049 15754 5490 0 1 46 0 0
cpu0 206 5 450 0 0 0 1 14 0 0
cpu1 81 0 3937 3149 1514 0 0 9 0 0
cpu2 45 6 332 6052 2243 0 0 11 0 0
cpu3 65 2 328 6552 1732 0 0 11 0 0
The idle and iowait states are weird 0 for cpu0(housekeeping).
The bug is present in both guest and host kernels, and they both have
cpu0's idle and iowait states issue, however, host kernel's suspend/resume
path etc will touch watchdog to avoid the softlockup.
- The watchdog will not be touched in tick_nohz_stop_idle path (need be
touched since the scheduler stall is expected) if idle_active flags are
not detected.
- The idle and iowait states will not be accounted when exit idle loop
(resched or interrupt) if idle start time and idle_active flags are
not set.
This patch fixes it by reverting commit 1f3b0f8243 since can't stop
idle tick doesn't mean can't be idle.
Fixes: 1f3b0f8243 ("tick/nohz: Optimize nohz idle enter")
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Sanjeev Yadav<sanjeev.yadav@spreadtrum.com>
Cc: Gaurav Jindal<gaurav.jindal@spreadtrum.com>
Cc: stable@vger.kernel.org
Cc: kvm@vger.kernel.org
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: http://lkml.kernel.org/r/1472798303-4154-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Merge fixes from Andrew Morton:
"14 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
rapidio/tsi721: fix incorrect detection of address translation condition
rapidio/documentation/mport_cdev: add missing parameter description
kernel/fork: fix CLONE_CHILD_CLEARTID regression in nscd
MAINTAINERS: Vladimir has moved
mm, mempolicy: task->mempolicy must be NULL before dropping final reference
printk/nmi: avoid direct printk()-s from __printk_nmi_flush()
treewide: remove references to the now unnecessary DEFINE_PCI_DEVICE_TABLE
drivers/scsi/wd719x.c: remove last declaration using DEFINE_PCI_DEVICE_TABLE
mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator
lib/test_hash.c: fix warning in preprocessor symbol evaluation
lib/test_hash.c: fix warning in two-dimensional array init
kconfig: tinyconfig: provide whole choice blocks to avoid warnings
kexec: fix double-free when failing to relocate the purgatory
mm, oom: prevent premature OOM killer invocation for high order request
Commit fec1d01152 ("[PATCH] Disable CLONE_CHILD_CLEARTID for abnormal
exit") has caused a subtle regression in nscd which uses
CLONE_CHILD_CLEARTID to clear the nscd_certainly_running flag in the
shared databases, so that the clients are notified when nscd is
restarted. Now, when nscd uses a non-persistent database, clients that
have it mapped keep thinking the database is being updated by nscd, when
in fact nscd has created a new (anonymous) one (for non-persistent
databases it uses an unlinked file as backend).
The original proposal for the CLONE_CHILD_CLEARTID change claimed
(https://lkml.org/lkml/2006/10/25/233):
: The NPTL library uses the CLONE_CHILD_CLEARTID flag on clone() syscalls
: on behalf of pthread_create() library calls. This feature is used to
: request that the kernel clear the thread-id in user space (at an address
: provided in the syscall) when the thread disassociates itself from the
: address space, which is done in mm_release().
:
: Unfortunately, when a multi-threaded process incurs a core dump (such as
: from a SIGSEGV), the core-dumping thread sends SIGKILL signals to all of
: the other threads, which then proceed to clear their user-space tids
: before synchronizing in exit_mm() with the start of core dumping. This
: misrepresents the state of process's address space at the time of the
: SIGSEGV and makes it more difficult for someone to debug NPTL and glibc
: problems (misleading him/her to conclude that the threads had gone away
: before the fault).
:
: The fix below is to simply avoid the CLONE_CHILD_CLEARTID action if a
: core dump has been initiated.
The resulting patch from Roland (https://lkml.org/lkml/2006/10/26/269)
seems to have a larger scope than the original patch asked for. It
seems that limitting the scope of the check to core dumping should work
for SIGSEGV issue describe above.
[Changelog partly based on Andreas' description]
Fixes: fec1d01152 ("[PATCH] Disable CLONE_CHILD_CLEARTID for abnormal exit")
Link: http://lkml.kernel.org/r/1471968749-26173-1-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Tested-by: William Preston <wpreston@suse.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Andreas Schwab <schwab@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
KASAN allocates memory from the page allocator as part of
kmem_cache_free(), and that can reference current->mempolicy through any
number of allocation functions. It needs to be NULL'd out before the
final reference is dropped to prevent a use-after-free bug:
BUG: KASAN: use-after-free in alloc_pages_current+0x363/0x370 at addr ffff88010b48102c
CPU: 0 PID: 15425 Comm: trinity-c2 Not tainted 4.8.0-rc2+ #140
...
Call Trace:
dump_stack
kasan_object_err
kasan_report_error
__asan_report_load2_noabort
alloc_pages_current <-- use after free
depot_save_stack
save_stack
kasan_slab_free
kmem_cache_free
__mpol_put <-- free
do_exit
This patch sets current->mempolicy to NULL before dropping the final
reference.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1608301442180.63329@chino.kir.corp.google.com
Fixes: cd11016e5f ("mm, kasan: stackdepot implementation. Enable stackdepot for SLAB")
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org> [4.6+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__printk_nmi_flush() can be called from nmi_panic(), therefore it has to
test whether it's executed in NMI context and thus must route the
messages through deferred printk() or via direct printk().
This is to avoid potential deadlocks, as described in commit
cf9b1106c8 ("printk/nmi: flush NMI messages on the system panic").
However there remain two places where __printk_nmi_flush() does
unconditional direct printk() calls:
- pr_err("printk_nmi_flush: internal error ...")
- pr_cont("\n")
Factor out print_nmi_seq_line() parts into a new printk_nmi_flush_line()
function, which takes care of in_nmi(), and use it in
__printk_nmi_flush() for printing and error-reporting.
Link: http://lkml.kernel.org/r/20160830161354.581-1-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Using "make tinyconfig" produces a couple of annoying warnings that show
up for build test machines all the time:
.config:966:warning: override: NOHIGHMEM changes choice state
.config:965:warning: override: SLOB changes choice state
.config:963:warning: override: KERNEL_XZ changes choice state
.config:962:warning: override: CC_OPTIMIZE_FOR_SIZE changes choice state
.config:933:warning: override: SLOB changes choice state
.config:930:warning: override: CC_OPTIMIZE_FOR_SIZE changes choice state
.config:870:warning: override: SLOB changes choice state
.config:868:warning: override: KERNEL_XZ changes choice state
.config:867:warning: override: CC_OPTIMIZE_FOR_SIZE changes choice state
I've made a previous attempt at fixing them and we discussed a number of
alternatives.
I tried changing the Makefile to use "merge_config.sh -n
$(fragment-list)" but couldn't get that to work properly.
This is yet another approach, based on the observation that we do want
to see a warning for conflicting 'choice' options, and that we can
simply make them non-conflicting by listing all other options as
disabled. This is a trivial patch that we can apply independent of
plans for other changes.
Link: http://lkml.kernel.org/r/20160829214952.1334674-2-arnd@arndb.de
Link: https://storage.kernelci.org/mainline/v4.7-rc6/x86-tinyconfig/build.loghttps://patchwork.kernel.org/patch/9212749/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If kexec_apply_relocations fails, kexec_load_purgatory frees pi->sechdrs
and pi->purgatory_buf. This is redundant, because in case of error
kimage_file_prepare_segments calls kimage_file_post_load_cleanup, which
will also free those buffers.
This causes two warnings like the following, one for pi->sechdrs and the
other for pi->purgatory_buf:
kexec-bzImage64: Loading purgatory failed
------------[ cut here ]------------
WARNING: CPU: 1 PID: 2119 at mm/vmalloc.c:1490 __vunmap+0xc1/0xd0
Trying to vfree() nonexistent vm area (ffffc90000e91000)
Modules linked in:
CPU: 1 PID: 2119 Comm: kexec Not tainted 4.8.0-rc3+ #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
dump_stack+0x4d/0x65
__warn+0xcb/0xf0
warn_slowpath_fmt+0x4f/0x60
? find_vmap_area+0x19/0x70
? kimage_file_post_load_cleanup+0x47/0xb0
__vunmap+0xc1/0xd0
vfree+0x2e/0x70
kimage_file_post_load_cleanup+0x5e/0xb0
SyS_kexec_file_load+0x448/0x680
? putname+0x54/0x60
? do_sys_open+0x190/0x1f0
entry_SYSCALL_64_fastpath+0x13/0x8f
---[ end trace 158bb74f5950ca2b ]---
Fix by setting pi->sechdrs an pi->purgatory_buf to NULL, since vfree
won't try to free a NULL pointer.
Link: http://lkml.kernel.org/r/1472083546-23683-1-git-send-email-bauerman@linux.vnet.ibm.com
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
David S. Miller
Josef Bacik
Shaohua Li
Linus Torvalds
Mickaël Salaün
Al Viro
Steven Rostedt (Red Hat)
Tejun Heo
Alexander Shishkin
Jakub Kicinski
Daniel Borkmann
Johannes Weiner
Marc Zyngier
Wei Yongjun
Joonwoo Park
Dan Williams
Arnd Bergmann
Balbir Singh
Peter Zijlstra
Alexei Starovoitov
Wanpeng Li
Michal Hocko
David Rientjes
Sergey Senozhatsky
Thiago Jung Bauermann