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| author | Michal Hocko <mhocko@suse.com> | 2018-04-11 02:29:52 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-16 11:10:24 +0300 |
| commit | 17ffa29c355658c8e9b19f56cbf0388500ca7905 (patch) | |
| tree | 60a459733ca06a62319e72369bb1744f57855839 /mm | |
| parent | ac91ff2a5f12309dc90404042e3ad788fab3cfdb (diff) | |
| download | linux-17ffa29c355658c8e9b19f56cbf0388500ca7905.tar.xz | |
memcg: fix per_node_info cleanup
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>
Diffstat (limited to 'mm')
| -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 66e7efabf0a1..546cd481a2ca 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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); } |