• Michal Hocko's avatar
    memcg: oom_notify use-after-free fix · 2bcf2e92
    Michal Hocko authored
    Paul Furtado has reported the following GPF:
      general protection fault: 0000 [#1] SMP
      Modules linked in: ipv6 dm_mod xen_netfront coretemp hwmon x86_pkg_temp_thermal crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel ablk_helper cryptd lrw gf128mul glue_helper aes_x86_64 microcode pcspkr ext4 jbd2 mbcache raid0 xen_blkfront
      CPU: 3 PID: 3062 Comm: java Not tainted 3.16.0-rc5 #1
      task: ffff8801cfe8f170 ti: ffff8801d2ec4000 task.ti: ffff8801d2ec4000
      RIP: e030:mem_cgroup_oom_synchronize+0x140/0x240
      RSP: e02b:ffff8801d2ec7d48  EFLAGS: 00010283
      RAX: 0000000000000001 RBX: ffff88009d633800 RCX: 000000000000000e
      RDX: fffffffffffffffe RSI: ffff88009d630200 RDI: ffff88009d630200
      RBP: ffff8801d2ec7da8 R08: 0000000000000012 R09: 00000000fffffffe
      R10: 0000000000000000 R11: 0000000000000000 R12: ffff88009d633800
      R13: ffff8801d2ec7d48 R14: dead000000100100 R15: ffff88009d633a30
      FS:  00007f1748bb4700(0000) GS:ffff8801def80000(0000) knlGS:0000000000000000
      CS:  e033 DS: 0000 ES: 0000 CR0: 000000008005003b
      CR2: 00007f4110300308 CR3: 00000000c05f7000 CR4: 0000000000002660
      Call Trace:
      Code: 44 00 00 48 89 df e8 40 ca ff ff 48 85 c0 49 89 c4 74 35 4c 8b b0 30 02 00 00 4c 8d b8 30 02 00 00 4d 39 fe 74 1b 0f 1f 44 00 00 <49> 8b 7e 10 be 01 00 00 00 e8 42 d2 04 00 4d 8b 36 4d 39 fe 75
      RIP  mem_cgroup_oom_synchronize+0x140/0x240
    Commit fb2a6fc5 ("mm: memcg: rework and document OOM waiting and
    wakeup") has moved mem_cgroup_oom_notify outside of memcg_oom_lock
    assuming it is protected by the hierarchical OOM-lock.
    Although this is true for the notification part the protection doesn't
    cover unregistration of event which can happen in parallel now so
    mem_cgroup_oom_notify can see already unlinked and/or freed
    Fix this by using memcg_oom_lock also in mem_cgroup_oom_notify.
    Addresses https://bugzilla.kernel.org/show_bug.cgi?id=80881
    Fixes: fb2a6fc5
     (mm: memcg: rework and document OOM waiting and wakeup)
    Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
    Reported-by: default avatarPaul Furtado <paulfurtado91@gmail.com>
    Tested-by: default avatarPaul Furtado <paulfurtado91@gmail.com>
    Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
    Cc: <stable@vger.kernel.org>	[3.12+]
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>