From 2bcf2e92c3918ce62ab4e934256e47e9a16d19c3 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Wed, 30 Jul 2014 16:08:33 -0700 Subject: memcg: oom_notify use-after-free fix 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: pagefault_out_of_memory+0x18/0x90 mm_fault_error+0xa9/0x1a0 __do_page_fault+0x478/0x4c0 do_page_fault+0x2c/0x40 page_fault+0x28/0x30 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 fb2a6fc56be6 ("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 mem_cgroup_eventfd_list. Fix this by using memcg_oom_lock also in mem_cgroup_oom_notify. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=80881 Fixes: fb2a6fc56be6 (mm: memcg: rework and document OOM waiting and wakeup) Signed-off-by: Michal Hocko Reported-by: Paul Furtado Tested-by: Paul Furtado Acked-by: Johannes Weiner Cc: [3.12+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a2c7bcb0e6eb..1f14a430c656 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5415,8 +5415,12 @@ static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg) { struct mem_cgroup_eventfd_list *ev; + spin_lock(&memcg_oom_lock); + list_for_each_entry(ev, &memcg->oom_notify, list) eventfd_signal(ev->eventfd, 1); + + spin_unlock(&memcg_oom_lock); return 0; } -- cgit v1.2.3