Patch "mm/mempool: avoid KASAN marking mempool poison checks as use-after-free" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

mm/mempool: avoid KASAN marking mempool poison checks as use-after-free

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-mempool-avoid-kasan-marking-mempool-poison-checks-as-use-after-free.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 <[email protected]> know about it.

From: Matthew Dawson <[email protected]>
Date: Fri, 11 Mar 2016 13:08:07 -0800
Subject: mm/mempool: avoid KASAN marking mempool poison checks as use-after-free

From: Matthew Dawson <[email protected]>

commit 7640131032db9118a78af715ac77ba2debeeb17c upstream.

When removing an element from the mempool, mark it as unpoisoned in KASAN before verifying its contents for SLUB/SLAB debugging. Otherwise KASAN will flag the reads checking the element use-after-free writes as use-after-free reads.

---
 mm/mempool.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -135,8 +135,8 @@ static void *remove_element(mempool_t *p
 	void *element = pool->elements[--pool->curr_nr];
 
 	BUG_ON(pool->curr_nr < 0);
-	check_element(pool, element);
 	kasan_unpoison_element(pool, element);
+	check_element(pool, element);
 	return element;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/mm-mempool-avoid-kasan-marking-mempool-poison-checks-as-use-after-free.patch