| From ee8c9d7c815ba144b93b56b151ec1ce767ed886e Mon Sep 17 00:00:00 2001 |
| From: Shakeel Butt <shakeelb@google.com> |
| Date: Tue, 5 Nov 2019 21:16:21 -0800 |
| Subject: [PATCH] mm: memcontrol: fix NULL-ptr deref in percpu stats flush |
| |
| commit 7961eee3978475fd9e8626137f88595b1ca05856 upstream. |
| |
| __mem_cgroup_free() can be called on the failure path in |
| mem_cgroup_alloc(). However memcg_flush_percpu_vmstats() and |
| memcg_flush_percpu_vmevents() which are called from __mem_cgroup_free() |
| access the fields of memcg which can potentially be null if called from |
| failure path from mem_cgroup_alloc(). Indeed syzbot has reported the |
| following crash: |
| |
| kasan: CONFIG_KASAN_INLINE enabled |
| kasan: GPF could be caused by NULL-ptr deref or user memory access |
| general protection fault: 0000 [#1] PREEMPT SMP KASAN |
| CPU: 0 PID: 30393 Comm: syz-executor.1 Not tainted 5.4.0-rc2+ #0 |
| Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 |
| RIP: 0010:memcg_flush_percpu_vmstats+0x4ae/0x930 mm/memcontrol.c:3436 |
| Code: 05 41 89 c0 41 0f b6 04 24 41 38 c7 7c 08 84 c0 0f 85 5d 03 00 00 44 3b 05 33 d5 12 08 0f 83 e2 00 00 00 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 0f 85 91 03 00 00 48 8b 85 10 fe ff ff 48 8b b0 90 |
| RSP: 0018:ffff888095c27980 EFLAGS: 00010206 |
| RAX: 0000000000000012 RBX: ffff888095c27b28 RCX: ffffc90008192000 |
| RDX: 0000000000040000 RSI: ffffffff8340fae7 RDI: 0000000000000007 |
| RBP: ffff888095c27be0 R08: 0000000000000000 R09: ffffed1013f0da33 |
| R10: ffffed1013f0da32 R11: ffff88809f86d197 R12: fffffbfff138b760 |
| R13: dffffc0000000000 R14: 0000000000000090 R15: 0000000000000007 |
| FS: 00007f5027170700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| CR2: 0000000000710158 CR3: 00000000a7b18000 CR4: 00000000001406f0 |
| DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 |
| DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 |
| Call Trace: |
| __mem_cgroup_free+0x1a/0x190 mm/memcontrol.c:5021 |
| mem_cgroup_free mm/memcontrol.c:5033 [inline] |
| mem_cgroup_css_alloc+0x3a1/0x1ae0 mm/memcontrol.c:5160 |
| css_create kernel/cgroup/cgroup.c:5156 [inline] |
| cgroup_apply_control_enable+0x44d/0xc40 kernel/cgroup/cgroup.c:3119 |
| cgroup_mkdir+0x899/0x11b0 kernel/cgroup/cgroup.c:5401 |
| kernfs_iop_mkdir+0x14d/0x1d0 fs/kernfs/dir.c:1124 |
| vfs_mkdir+0x42e/0x670 fs/namei.c:3807 |
| do_mkdirat+0x234/0x2a0 fs/namei.c:3830 |
| __do_sys_mkdir fs/namei.c:3846 [inline] |
| __se_sys_mkdir fs/namei.c:3844 [inline] |
| __x64_sys_mkdir+0x5c/0x80 fs/namei.c:3844 |
| do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 |
| entry_SYSCALL_64_after_hwframe+0x49/0xbe |
| |
| Fixing this by moving the flush to mem_cgroup_free as there is no need |
| to flush anything if we see failure in mem_cgroup_alloc(). |
| |
| Link: http://lkml.kernel.org/r/20191018165231.249872-1-shakeelb@google.com |
| Fixes: bb65f89b7d3d ("mm: memcontrol: flush percpu vmevents before releasing memcg") |
| Fixes: c350a99ea2b1 ("mm: memcontrol: flush percpu vmstats before releasing memcg") |
| Signed-off-by: Shakeel Butt <shakeelb@google.com> |
| Reported-by: syzbot+515d5bcfe179cdf049b2@syzkaller.appspotmail.com |
| Reviewed-by: Roman Gushchin <guro@fb.com> |
| Cc: Michal Hocko <mhocko@suse.com> |
| Cc: Johannes Weiner <hannes@cmpxchg.org> |
| Cc: Vladimir Davydov <vdavydov.dev@gmail.com> |
| Cc: <stable@vger.kernel.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/mm/memcontrol.c b/mm/memcontrol.c |
| index d1debb6a5178..13cd83f5ceb4 100644 |
| --- a/mm/memcontrol.c |
| +++ b/mm/memcontrol.c |
| @@ -4622,12 +4622,6 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg) |
| { |
| int node; |
| |
| - /* |
| - * Flush percpu vmstats and vmevents to guarantee the value correctness |
| - * on parent's and all ancestor levels. |
| - */ |
| - memcg_flush_percpu_vmstats(memcg); |
| - memcg_flush_percpu_vmevents(memcg); |
| for_each_node(node) |
| free_mem_cgroup_per_node_info(memcg, node); |
| free_percpu(memcg->vmstats_percpu); |
| @@ -4638,6 +4632,12 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg) |
| static void mem_cgroup_free(struct mem_cgroup *memcg) |
| { |
| memcg_wb_domain_exit(memcg); |
| + /* |
| + * Flush percpu vmstats and vmevents to guarantee the value correctness |
| + * on parent's and all ancestor levels. |
| + */ |
| + memcg_flush_percpu_vmstats(memcg); |
| + memcg_flush_percpu_vmevents(memcg); |
| __mem_cgroup_free(memcg); |
| } |
| |
| -- |
| 2.7.4 |
| |
