iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

memcg: fix per_node_info cleanup

Browse Source 
commit 4eaf431f6f71bbed40a4c733ffe93a7e8cedf9d9 upstream.

syzbot has triggered a NULL ptr dereference when allocation fault
injection enforces a failure and alloc_mem_cgroup_per_node_info
initializes memcg->nodeinfo only half way through.

But __mem_cgroup_free still tries to free all per-node data and
dereferences pn->lruvec_stat_cpu unconditioanlly even if the specific
per-node data hasn't been initialized.

The bug is quite unlikely to hit because small allocations do not fail
and we would need quite some numa nodes to make struct
mem_cgroup_per_node large enough to cross the costly order.

Link: http://lkml.kernel.org/r/20180406100906.17790-1-mhocko@kernel.org
Reported-by: syzbot+8a5de3cce7cdc70e9ebe@syzkaller.appspotmail.com
Fixes: 00f3ca2c2d66 ("mm: memcontrol: per-lruvec stats infrastructure")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michal Hocko 2018-04-10 16:29:52 -07:00 committed by Greg Kroah-Hartman
parent ac91ff2a5f
commit 17ffa29c35
1 changed files with 3 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
mm/memcontrol.c
View File

@ -4187,6 +4187,9 @@ static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
{
struct mem_cgroup_per_node *pn = memcg->nodeinfo[node];
if (!pn)
return;
free_percpu(pn->lruvec_stat);
kfree(pn);
}