The patch titled
Subject: mm/list_lru.c: avoid error-path NULL pointer deref
has been added to the -mm tree. Its filename is
mm-list_lruc-avoid-error-path-null-pointer-deref.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-list_lruc-avoid-error-path-null-pointer-deref.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-list_lruc-avoid-error-path-null-pointer-deref.patch
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------------------------------------------------------
From: Alexander Polakov <apolyakov@xxxxxxxx>
Subject: 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@xxxxxxxxxxxxxxxxxxxx: add comment]
Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/list_lru.c | 2 ++
1 file changed, 2 insertions(+)
diff -puN mm/list_lru.c~mm-list_lruc-avoid-error-path-null-pointer-deref mm/list_lru.c
--- a/mm/list_lru.c~mm-list_lruc-avoid-error-path-null-pointer-deref
+++ a/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 -mm which might be from apolyakov@xxxxxxxx are
mm-list_lruc-avoid-error-path-null-pointer-deref.patch
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