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| author | Michal Hocko <mhocko@suse.com> | 2018-04-10 16:29:52 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-04-11 10:28:32 -0700 |
| commit | 4eaf431f6f71bbed40a4c733ffe93a7e8cedf9d9 (patch) | |
| tree | b4121b55c22e052d0847796ad22574eaedf281d6 /mm/memcontrol.c | |
| parent | a06ad633a37c64a0cd4c229fc605cee8725d376e (diff) | |
| download | lwn-4eaf431f6f71bbed40a4c733ffe93a7e8cedf9d9.tar.gz lwn-4eaf431f6f71bbed40a4c733ffe93a7e8cedf9d9.zip | |
memcg: fix per_node_info cleanup
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>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f314334546a2..7978c6faae06 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4108,6 +4108,9 @@ 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_cpu); kfree(pn); } |