linux/net/core
Andrey Ryabinin 40eea803c6 net: sendmsg: fix NULL pointer dereference
Sasha's report:
	> While fuzzing with trinity inside a KVM tools guest running the latest -next
	> kernel with the KASAN patchset, I've stumbled on the following spew:
	>
	> [ 4448.949424] ==================================================================
	> [ 4448.951737] AddressSanitizer: user-memory-access on address 0
	> [ 4448.952988] Read of size 2 by thread T19638:
	> [ 4448.954510] CPU: 28 PID: 19638 Comm: trinity-c76 Not tainted 3.16.0-rc4-next-20140711-sasha-00046-g07d3099-dirty #813
	> [ 4448.956823]  ffff88046d86ca40 0000000000000000 ffff880082f37e78 ffff880082f37a40
	> [ 4448.958233]  ffffffffb6e47068 ffff880082f37a68 ffff880082f37a58 ffffffffb242708d
	> [ 4448.959552]  0000000000000000 ffff880082f37a88 ffffffffb24255b1 0000000000000000
	> [ 4448.961266] Call Trace:
	> [ 4448.963158] dump_stack (lib/dump_stack.c:52)
	> [ 4448.964244] kasan_report_user_access (mm/kasan/report.c:184)
	> [ 4448.965507] __asan_load2 (mm/kasan/kasan.c:352)
	> [ 4448.966482] ? netlink_sendmsg (net/netlink/af_netlink.c:2339)
	> [ 4448.967541] netlink_sendmsg (net/netlink/af_netlink.c:2339)
	> [ 4448.968537] ? get_parent_ip (kernel/sched/core.c:2555)
	> [ 4448.970103] sock_sendmsg (net/socket.c:654)
	> [ 4448.971584] ? might_fault (mm/memory.c:3741)
	> [ 4448.972526] ? might_fault (./arch/x86/include/asm/current.h:14 mm/memory.c:3740)
	> [ 4448.973596] ? verify_iovec (net/core/iovec.c:64)
	> [ 4448.974522] ___sys_sendmsg (net/socket.c:2096)
	> [ 4448.975797] ? put_lock_stats.isra.13 (./arch/x86/include/asm/preempt.h:98 kernel/locking/lockdep.c:254)
	> [ 4448.977030] ? lock_release_holdtime (kernel/locking/lockdep.c:273)
	> [ 4448.978197] ? lock_release_non_nested (kernel/locking/lockdep.c:3434 (discriminator 1))
	> [ 4448.979346] ? check_chain_key (kernel/locking/lockdep.c:2188)
	> [ 4448.980535] __sys_sendmmsg (net/socket.c:2181)
	> [ 4448.981592] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2600)
	> [ 4448.982773] ? trace_hardirqs_on (kernel/locking/lockdep.c:2607)
	> [ 4448.984458] ? syscall_trace_enter (arch/x86/kernel/ptrace.c:1500 (discriminator 2))
	> [ 4448.985621] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2600)
	> [ 4448.986754] SyS_sendmmsg (net/socket.c:2201)
	> [ 4448.987708] tracesys (arch/x86/kernel/entry_64.S:542)
	> [ 4448.988929] ==================================================================

This reports means that we've come to netlink_sendmsg() with msg->msg_name == NULL and msg->msg_namelen > 0.

After this report there was no usual "Unable to handle kernel NULL pointer dereference"
and this gave me a clue that address 0 is mapped and contains valid socket address structure in it.

This bug was introduced in f3d3342602
(net: rework recvmsg handler msg_name and msg_namelen logic).
Commit message states that:
	"Set msg->msg_name = NULL if user specified a NULL in msg_name but had a
	 non-null msg_namelen in verify_iovec/verify_compat_iovec. This doesn't
	 affect sendto as it would bail out earlier while trying to copy-in the
	 address."
But in fact this affects sendto when address 0 is mapped and contains
socket address structure in it. In such case copy-in address will succeed,
verify_iovec() function will successfully exit with msg->msg_namelen > 0
and msg->msg_name == NULL.

This patch fixes it by setting msg_namelen to 0 if msg_name == NULL.

Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: <stable@vger.kernel.org>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-07-29 12:20:22 -07:00
..
Makefile net: Add a software TSO helper API 2014-05-22 14:57:15 -04:00
datagram.c net: Fix save software checksum complete 2014-06-15 01:00:49 -07:00
dev.c net-gre-gro: Fix a bug that breaks the forwarding path 2014-07-16 14:45:26 -07:00
dev_addr_lists.c net: Add support for device specific address syncing 2014-06-02 10:40:54 -07:00
dev_ioctl.c net_tstamp: Add SIOCGHWTSTAMP ioctl to match SIOCSHWTSTAMP 2013-11-19 19:07:21 +00:00
drop_monitor.c net: drop_monitor: fix the value of maxattr 2013-12-09 21:10:38 -05:00
dst.c ipv4: fix dst race in sk_dst_get() 2014-06-25 17:41:44 -07:00
ethtool.c ethtool: Check that reserved fields of struct ethtool_rxfh are 0 2014-06-03 02:43:16 +01:00
fib_rules.c net: fix 'ip rule' iif/oif device rename 2014-02-09 19:02:52 -08:00
filter.c net: filter: Use kcalloc/kmalloc_array to allocate arrays 2014-06-25 16:40:02 -07:00
flow.c CPU hotplug notifiers registration fixes for 3.15-rc1 2014-04-07 14:55:46 -07:00
flow_dissector.c net: Rename skb->rxhash to skb->hash 2014-03-26 15:58:20 -04:00
gen_estimator.c net_sched: add 64bit rate estimators 2013-06-11 02:51:03 -07:00
gen_stats.c net_sched: add 64bit rate estimators 2013-06-11 02:51:03 -07:00
iovec.c net: sendmsg: fix NULL pointer dereference 2014-07-29 12:20:22 -07:00
link_watch.c arch: Mass conversion of smp_mb__*() 2014-04-18 14:20:48 +02:00
neighbour.c neighbour : fix ndm_type type error issue 2014-07-28 17:52:17 -07:00
net-procfs.c rps: selective flow shedding during softnet overflow 2013-05-20 13:48:04 -07:00
net-sysfs.c Revert "net: return actual error on register_queue_kobjects" 2014-06-19 18:12:15 -07:00
net-sysfs.h net: netdev_kobject_init: annotate with __init 2014-01-05 20:27:54 -05:00
net-traces.c net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules 2011-10-31 19:30:30 -04:00
net_namespace.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-05-24 00:32:30 -04:00
netclassid_cgroup.c cgroup: remove css_parent() 2014-05-16 13:22:48 -04:00
netevent.c net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules 2011-10-31 19:30:30 -04:00
netpoll.c netpoll: Use skb_irq_freeable to make zap_completion_queue safe. 2014-04-01 17:53:36 -04:00
netprio_cgroup.c cgroup: remove css_parent() 2014-05-16 13:22:48 -04:00
pktgen.c pktgen: Use seq_puts() where seq_printf() is not needed 2014-05-16 17:30:30 -04:00
ptp_classifier.c net: filter: let unattached filters use sock_fprog_kern 2014-05-23 16:48:05 -04:00
request_sock.c net: remove unnecessary return's 2014-02-13 18:33:38 -05:00
rtnetlink.c rtnetlink: fix userspace API breakage for iproute2 < v3.9.0 2014-06-12 11:07:42 -07:00
scm.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
secure_seq.c inetpeer: get rid of ip_id_count 2014-06-02 11:00:41 -07:00
skbuff.c net: fix setting csum_start in skb_segment() 2014-06-25 20:45:54 -07:00
sock.c net: Split sk_no_check into sk_no_check_{rx,tx} 2014-05-23 16:28:53 -04:00
sock_diag.c net: Move the permission check in sock_diag_put_filterinfo to packet_diag_dump 2014-04-24 13:44:53 -04:00
stream.c net: replace macros net_random and net_srandom with direct calls to prandom 2014-01-14 15:15:25 -08:00
sysctl_net_core.c rps: NUMA flow limit allocations 2013-12-19 19:00:07 -05:00
timestamping.c net: ptp: move PTP classifier in its own file 2014-04-01 16:43:18 -04:00
tso.c net: tso: Export symbols for modular build 2014-05-30 15:52:03 -07:00
user_dma.c net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules 2011-10-31 19:30:30 -04:00
utils.c net: avoid dependency of net_get_random_once on nop patching 2014-05-14 00:37:34 -04:00