| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.8 019/138] mm/list_lru.c: avoid error-path NULL pointer deref | Date | Wed, 9 Nov 2016 11:45:02 +0100 |
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4.8-stable review patch. If anyone has any objections, please let me know.
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From: Alexander Polakov <apolyakov@beget.ru>
commit 1bc11d70b5db7c6bb1414b283d7f09b1fe1ac0d0 upstream.
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> 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>
--- mm/list_lru.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -554,6 +554,8 @@ int __list_lru_init(struct list_lru *lru 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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