memcontrol: fix potential null deref

There was a potential null deref introduced in c62b1a3b31b5 ("memcg: use
generic percpu instead of private implementation").

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 00dda352144c..9ed760dc7448 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3691,8 +3691,10 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
         else
                 mem = vmalloc(size);
 
-        if (mem)
-                memset(mem, 0, size);
+        if (!mem)
+                return NULL;
+
+        memset(mem, 0, size);
         mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
         if (!mem->stat) {
                 if (size < PAGE_SIZE)