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Thomas Gleixner 5666a3de7a genirq: Prevent proc race against freeing of irq descriptors 
commit c291ee6221 upstream.

Since the rework of the sparse interrupt code to actually free the
unused interrupt descriptors there exists a race between the /proc
interfaces to the irq subsystem and the code which frees the interrupt
descriptor.

CPU0				CPU1
				show_interrupts()
				  desc = irq_to_desc(X);
free_desc(desc)
  remove_from_radix_tree();
  kfree(desc);
				  raw_spinlock_irq(&desc->lock);

/proc/interrupts is the only interface which can actively corrupt
kernel memory via the lock access. /proc/stat can only read from freed
memory. Extremly hard to trigger, but possible.

The interfaces in /proc/irq/N/ are not affected by this because the
removal of the proc file is serialized in procfs against concurrent
readers/writers. The removal happens before the descriptor is freed.

For architectures which have CONFIG_SPARSE_IRQ=n this is a non issue
as the descriptor is never freed. It's merely cleared out with the irq
descriptor lock held. So any concurrent proc access will either see
the old correct value or the cleared out ones.

Protect the lookup and access to the irq descriptor in
show_interrupts() with the sparse_irq_lock.

Provide kstat_irqs_usr() which is protecting the lookup and access
with sparse_irq_lock and switch /proc/stat to use it.

Document the existing kstat_irqs interfaces so it's clear that the
caller needs to take care about protection. The users of these
interfaces are either not affected due to SPARSE_IRQ=n or already
protected against removal.

Fixes: 1f5a5b87f7 "genirq: Implement a sane sparse_irq allocator"
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2015-01-27 08:18:55 -08:00
..
cpu sched/preempt: Fix up missed PREEMPT_NEED_RESCHED folding 2014-01-13 17:38:55 +01:00
debug mm: per-thread vma caching 2014-10-09 12:21:29 -07:00
events perf: Fix events installation during moving group 2015-01-16 06:59:34 -08:00
gcov gcov: reuse kbasename helper 2013-11-13 12:09:34 +09:00
irq genirq: Prevent proc race against freeing of irq descriptors 2015-01-27 08:18:55 -08:00
locking rtmutex: Plug slow unlock race 2014-06-30 20:11:58 -07:00
power PM / Sleep: fix recovery during resuming from hibernation 2014-11-14 09:00:10 -08:00
printk printk: rename printk_sched to printk_deferred 2014-08-07 14:52:37 -07:00
rcu rcu: Use rcu_gp_kthread_wake() to wake up grace period kthreads 2014-11-21 09:23:05 -08:00
sched sched/deadline: Avoid double-accounting in case of missed deadlines 2015-01-16 06:59:33 -08:00
time tick/powerclamp: Remove tick_nohz_idle abuse 2015-01-27 08:18:55 -08:00
trace tracing/syscalls: Ignore numbers outside NR_syscalls' range 2014-11-14 08:59:42 -08:00
.gitignore Ignore generated file kernel/x509_certificate_list 2013-12-10 18:21:34 +00:00
Kconfig.freezer
…
Kconfig.hz kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS 2013-11-15 09:32:22 +09:00
Kconfig.locks locking/mutex: Disable optimistic spinning on some architectures 2014-07-28 08:06:03 -07:00
Kconfig.preempt
…
Makefile KEYS: Remove files generated when SYSTEM_TRUSTED_KEYRING=y 2013-12-13 15:59:11 +00:00
acct.c fs: Fix hang with BSD accounting on frozen filesystem 2013-05-04 14:57:58 -04:00
async.c async: rename and redefine async_func_ptr 2013-03-12 13:59:14 -07:00
audit.c audit: AUDIT_FEATURE_CHANGE message format missing delimiting space 2014-11-21 09:23:01 -08:00
audit.h audit: Use struct net not pid_t to remember the network namespce to reply in 2014-02-28 04:04:33 -08:00
audit_tree.c audit: keep inode pinned 2014-11-21 09:23:01 -08:00
audit_watch.c inotify: Fix reporting of cookies for inotify events 2014-02-18 11:17:17 +01:00
auditfilter.c audit: restore AUDIT_LOGINUID unset ABI 2015-01-08 10:00:50 -08:00
auditsc.c audit: remove superfluous new- prefix in AUDIT_LOGIN messages 2014-07-09 11:18:28 -07:00
backtracetest.c
…
bounds.c mm: do not allocate page->ptl dynamically, if spinlock_t fits to long 2013-12-20 12:25:45 -08:00
capability.c CAPABILITIES: remove undefined caps from all processes 2014-09-17 09:19:09 -07:00
cgroup.c cgroup: fix unbalanced locking 2014-10-05 14:52:17 -07:00
cgroup_freezer.c cgroup: replace cftype->read_seq_string() with cftype->seq_show() 2013-12-05 12:28:04 -05:00
compat.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-05-01 07:21:43 -07:00
configs.c proc: Supply PDE attribute setting accessor functions 2013-05-01 17:29:18 -04:00
context_tracking.c context_tracking: Wrap static key check into more intuitive function name 2013-12-02 20:43:14 +01:00
cpu.c sched: Fix hotplug vs. set_cpus_allowed_ptr() 2014-06-11 11:54:11 -07:00
cpu_pm.c
…
cpuset.c mm: optimize put_mems_allowed() usage 2014-10-09 12:21:28 -07:00
crash_dump.c
…
cred.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2012-12-18 10:55:28 -08:00
delayacct.c kernel/delayacct.c: remove redundant checking in __delayacct_add_tsk() 2013-11-13 12:09:12 +09:00
dma.c
…
elfcore.c switch elf_core_write_extra_phdrs() to dump_emit() 2013-11-09 00:16:23 -05:00
exec_domain.c
…
exit.c exit: call disassociate_ctty() before exit_task_namespaces() 2014-04-26 17:19:07 -07:00
extable.c kernel/extable: fix address-checks for core_kernel and init areas 2013-11-28 09:49:41 -08:00
fork.c mm: per-thread vma caching 2014-10-09 12:21:29 -07:00
freezer.c freezer: Do not freeze tasks killed by OOM killer 2014-11-14 09:00:01 -08:00
futex.c futex: Ensure get_futex_key_refs() always implies a barrier 2014-10-30 09:38:24 -07:00
futex_compat.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-02-23 18:50:11 -08:00
groups.c userns: Don't allow setgroups until a gid mapping has been setablished 2015-01-08 10:00:50 -08:00
hrtimer.c hrtimer: Set expiry time before switch_hrtimer_base() 2014-06-07 10:28:12 -07:00
hung_task.c hung_task: Display every hung task warning 2014-01-25 12:13:33 +01:00
irq_work.c Merge branch 'nohz/printk-v8' into irq/core 2013-02-05 00:48:46 +01:00
itimer.c
…
jump_label.c static_key: WARN on usage before jump_label_init was called 2013-10-19 19:45:35 -04:00
kallsyms.c kernel: kallsyms: memory override issue, need check destination buffer length 2013-04-15 15:17:26 +09:30
kcmp.c kcmp: fix standard comparison bug 2014-10-05 14:52:20 -07:00
kexec.c powerpc, kexec: Fix "Processor X is stuck" issue during kexec from ST mode 2014-06-07 10:28:28 -07:00
kmod.c execve: use 'struct filename *' for executable name passing 2014-02-05 12:54:53 -08:00
kprobes.c kprobes: use KSYM_NAME_LEN to size identifier buffers 2013-11-13 12:09:26 +09:00
ksysfs.c kdump: fix exported size of vmcoreinfo note 2014-01-23 16:37:03 -08:00
kthread.c kthread: fix return value of kthread_create() upon SIGKILL. 2014-06-30 20:11:53 -07:00
latencytop.c
…
module-internal.h KEYS: Separate the kernel signature checking keyring from module signing 2013-09-25 17:17:01 +01:00
module.c modules, lock around setting of MODULE_STATE_UNFORMED 2014-11-14 08:59:52 -08:00
module_signing.c keys: change asymmetric keys to use common hash definitions 2013-10-25 17:15:18 -04:00
notifier.c
…
nsproxy.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2013-09-07 14:35:32 -07:00
padata.c padata: Fix wrong usage of rcu_dereference() 2013-12-05 21:28:42 +08:00
panic.c panic: Make panic_timeout configurable 2013-11-26 12:12:26 +01:00
params.c params: improve standard definitions 2013-12-04 14:09:46 +10:30
pid.c exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting 2015-01-08 10:00:50 -08:00
pid_namespace.c pid_namespace: pidns_get() should check task_active_pid_ns() != NULL 2014-04-26 17:19:04 -07:00
posix-cpu-timers.c posix-timers: Convert abuses of BUG_ON to WARN_ON 2013-12-09 16:56:29 +01:00
posix-timers.c posix-timers: Fix stack info leak in timer_create() 2014-11-14 09:00:10 -08:00
profile.c mm: fix GFP_THISNODE callers and clarify 2014-03-10 17:26:19 -07:00
ptrace.c exec/ptrace: fix get_dumpable() incorrect tests 2013-11-13 12:09:33 +09:00
range.c range: Do not add new blank slot with add_range_with_merge 2013-06-18 11:32:10 -05:00
reboot.c kexec: migrate to reboot cpu 2013-12-18 19:04:50 -08:00
relay.c kernel: delete __cpuinit usage from all core kernel files 2013-07-14 19:36:59 -04:00
res_counter.c memcg: reduce function dereference 2013-09-12 15:38:02 -07:00
resource.c kernel/resource.c: remove the unneeded assignment in function __find_resource 2013-07-03 16:08:06 -07:00
seccomp.c seccomp: allow BPF_XOR based ALU instructions. 2013-03-26 11:07:19 +11:00
signal.c kernel/signal.c: change do_signal_stop/do_sigaction to use while_each_thread() 2014-01-23 16:37:02 -08:00
smp.c kernel/smp.c:on_each_cpu_cond(): fix warning in fallback path 2014-09-17 09:19:09 -07:00
smpboot.c kernel: delete __cpuinit usage from all core kernel files 2013-07-14 19:36:59 -04:00
smpboot.h
…
softirq.c Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-01-31 09:02:51 -08:00
stacktrace.c
…
stop_machine.c stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus() 2014-03-11 11:33:47 +01:00
sys.c kernel/sys.c: k_getrusage() can use while_each_thread() 2014-01-23 16:37:02 -08:00
sys_ni.c unify compat fanotify_mark(2), switch to COMPAT_SYSCALL_DEFINE 2013-05-09 13:46:38 -04:00
sysctl.c mm, pcp: allow restoring percpu_pagelist_fraction default 2014-07-09 11:18:26 -07:00
sysctl_binary.c kernel/sysctl_binary.c: use scnprintf() instead of snprintf() 2013-11-13 12:09:33 +09:00
system_certificates.S KEYS: correct alignment of system_certificate_list content in assembly file 2013-12-10 18:25:28 +00:00
system_keyring.c KEYS: correct alignment of system_certificate_list content in assembly file 2013-12-10 18:25:28 +00:00
task_work.c task_work: documentation 2013-09-11 15:58:27 -07:00
taskstats.c genetlink: only pass array to genl_register_family_with_ops() 2013-11-19 16:39:05 -05:00
test_kprobes.c kernel/: rename random32() to prandom_u32() 2013-04-29 18:28:42 -07:00
time.c jiffies: Fix timeval conversion to jiffies 2014-10-09 12:21:27 -07:00
timeconst.bc kernel: Replace timeconst.pl with a bc script 2013-02-16 23:17:25 +01:00
timer.c timer: Prevent overflow in apply_slack 2014-06-07 10:28:09 -07:00
tracepoint.c tracepoint: Do not waste memory on mods with no tracepoints 2014-05-31 13:20:28 -07:00
tsacct.c cputime: Use accessors to read task cputime stats 2013-01-27 19:23:31 +01:00
uid16.c groups: Consolidate the setgroups permission checks 2015-01-08 10:00:49 -08:00
up.c kernel: provide a __smp_call_function_single stub for !CONFIG_SMP 2013-11-15 09:32:22 +09:00
user-return-notifier.c hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
user.c userns: Add a knob to disable setgroups on a per user namespace basis 2015-01-08 10:00:50 -08:00
user_namespace.c userns: Allow setting gid_maps without privilege when setgroups is disabled 2015-01-08 10:00:50 -08:00
utsname.c userns: Kill nsown_capable it makes the wrong thing easy 2013-08-30 23:44:11 -07:00
utsname_sysctl.c kernel/utsname_sysctl.c: put get/get_uts() into CONFIG_PROC_SYSCTL code block 2013-02-27 19:10:22 -08:00
watchdog.c kernel/watchdog.c: remove preemption restrictions when restarting lockup detector 2014-07-06 18:57:27 -07:00
workqueue.c workqueue: zero cpumask of wq_numa_possible_cpumask on init 2014-07-17 16:21:03 -07:00
workqueue_internal.h sched: Rename sched.c as sched/core.c in comments and Documentation 2013-06-19 12:58:42 +02:00