4.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tejun Heo <tj@xxxxxxxxxx>
commit ea3a9645866e12d2b198434f03df3c3e96fb86ce upstream.
mem_cgroup_css_alloc() was returning NULL on failure while cgroup core
expected it to return an ERR_PTR value leading to the following NULL
deref after a css allocation failure. Fix it by return
ERR_PTR(-ENOMEM) instead. I'll also update cgroup core so that it
can handle NULL returns.
mkdir: page allocation failure: order:6, mode:0x240c0c0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO)
CPU: 0 PID: 8738 Comm: mkdir Not tainted 4.7.0-rc3+ #123
...
Call Trace:
dump_stack+0x68/0xa1
warn_alloc_failed+0xd6/0x130
__alloc_pages_nodemask+0x4c6/0xf20
alloc_pages_current+0x66/0xe0
alloc_kmem_pages+0x14/0x80
kmalloc_order_trace+0x2a/0x1a0
__kmalloc+0x291/0x310
memcg_update_all_caches+0x6c/0x130
mem_cgroup_css_alloc+0x590/0x610
cgroup_apply_control_enable+0x18b/0x370
cgroup_mkdir+0x1de/0x2e0
kernfs_iop_mkdir+0x55/0x80
vfs_mkdir+0xb9/0x150
SyS_mkdir+0x66/0xd0
do_syscall_64+0x53/0x120
entry_SYSCALL64_slow_path+0x25/0x25
...
BUG: unable to handle kernel NULL pointer dereference at 00000000000000d0
IP: init_and_link_css+0x37/0x220
PGD 34b1e067 PUD 3a109067 PMD 0
Oops: 0002 [#1] SMP
Modules linked in:
CPU: 0 PID: 8738 Comm: mkdir Not tainted 4.7.0-rc3+ #123
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.2-20160422_131301-anatol 04/01/2014
task: ffff88007cbc5200 ti: ffff8800666d4000 task.ti: ffff8800666d4000
RIP: 0010:[<ffffffff810f2ca7>] [<ffffffff810f2ca7>] init_and_link_css+0x37/0x220
RSP: 0018:ffff8800666d7d90 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffffffff810f2499 RSI: 0000000000000000 RDI: 0000000000000008
RBP: ffff8800666d7db8 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff88005a5fb400
R13: ffffffff81f0f8a0 R14: ffff88005a5fb400 R15: 0000000000000010
FS: 00007fc944689700(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3aed0d2b80 CR3: 000000003a1e8000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
cgroup_apply_control_enable+0x1ac/0x370
cgroup_mkdir+0x1de/0x2e0
kernfs_iop_mkdir+0x55/0x80
vfs_mkdir+0xb9/0x150
SyS_mkdir+0x66/0xd0
do_syscall_64+0x53/0x120
entry_SYSCALL64_slow_path+0x25/0x25
Code: 89 f5 48 89 fb 49 89 d4 48 83 ec 08 8b 05 72 3b d8 00 85 c0 0f 85 60 01 00 00 4c 89 e7 e8 72 f7 ff ff 48 8d 7b 08 48 89 d9 31 c0 <48> c7 83 d0 00 00 00 00 00 00 00 48 83 e7 f8 48 29 f9 81 c1 d8
RIP init_and_link_css+0x37/0x220
RSP <ffff8800666d7d90>
CR2: 00000000000000d0
---[ end trace a2d8836ae1e852d1 ]---
Link: http://lkml.kernel.org/r/20160621165740.GJ3262@xxxxxxxxxxxxxxx
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Reported-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4184,7 +4184,7 @@ mem_cgroup_css_alloc(struct cgroup_subsy
return &memcg->css;
fail:
mem_cgroup_free(memcg);
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
static int
--
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