This is a note to let you know that I've just added the patch titled
mm/list_lru.c: avoid error-path NULL pointer deref
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-list_lru.c-avoid-error-path-null-pointer-deref.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1bc11d70b5db7c6bb1414b283d7f09b1fe1ac0d0 Mon Sep 17 00:00:00 2001
From: Alexander Polakov <apolyakov@xxxxxxxx>
Date: Thu, 27 Oct 2016 17:46:27 -0700
Subject: mm/list_lru.c: avoid error-path NULL pointer deref
From: Alexander Polakov <apolyakov@xxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxx: add comment]
Signed-off-by: Alexander Polakov <apolyakov@xxxxxxxx>
Acked-by: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
Patches currently in stable-queue which might be from apolyakov@xxxxxxxx are
queue-4.4/mm-list_lru.c-avoid-error-path-null-pointer-deref.patch
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