Commit 1bc11d70 authored Oct 27, 2016 by Alexander Polakov Committed by Linus Torvalds Oct 27, 2016

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

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: Alexander Polakov <apolyakov@beget.ru>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 21753583

mm/list_lru.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -554,6 +554,8 @@ 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;
		}