Commit 55a2f87c authored by Alexander Polakov's avatar Alexander Polakov Committed by Sasha Levin

mm/list_lru.c: avoid error-path NULL pointer deref

[ Upstream commit 1bc11d70 ]

As described in https://bugzilla.kernel.org/show_bug.cgi?id=177821:

After some analysis it seems to be that the problem is in alloc_super().
In case list_lru_init_memcg() fails it goes into destroy_super(), which
calls list_lru_destroy().

And in list_lru_init() we see that in case memcg_init_list_lru() fails,
lru->node is freed, but not set NULL, which then leads list_lru_destroy()
to believe it is initialized and call memcg_destroy_list_lru().
memcg_destroy_list_lru() in turn can access lru->node[i].memcg_lrus,
which is NULL.

[akpm@linux-foundation.org: add comment]
Signed-off-by: default avatarAlexander Polakov <apolyakov@beget.ru>
Acked-by: default avatarVladimir Davydov <vdavydov.dev@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent 52e7b6bd
......@@ -532,6 +532,8 @@ int __list_lru_init(struct list_lru *lru, bool memcg_aware,
err = memcg_init_list_lru(lru, memcg_aware);
if (err) {
kfree(lru->node);
/* Do this so a list_lru_destroy() doesn't crash: */
lru->node = NULL;
goto out;
}
......
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