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From: Matthew Dawson <matthew@mjdsystems.ca>
To: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] mm/mempool: Avoid KASAN marking mempool posion checks as use-after-free
Date: Wed,  9 Mar 2016 01:16:19 -0500	[thread overview]
Message-ID: <1457504179-18942-1-git-send-email-matthew@mjdsystems.ca> (raw)

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.

Signed-off-by: Matthew Dawson <matthew@mjdsystems.ca>
---
 mm/mempool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mempool.c b/mm/mempool.c
index 004d42b..7924f4f 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -135,8 +135,8 @@ static void *remove_element(mempool_t *pool)
 	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;
 }
 
-- 
2.7.1

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WARNING: multiple messages have this Message-ID (diff)
From: Matthew Dawson <matthew@mjdsystems.ca>
To: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] mm/mempool: Avoid KASAN marking mempool posion checks as use-after-free
Date: Wed,  9 Mar 2016 01:16:19 -0500	[thread overview]
Message-ID: <1457504179-18942-1-git-send-email-matthew@mjdsystems.ca> (raw)

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.

Signed-off-by: Matthew Dawson <matthew@mjdsystems.ca>
---
 mm/mempool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mempool.c b/mm/mempool.c
index 004d42b..7924f4f 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -135,8 +135,8 @@ static void *remove_element(mempool_t *pool)
 	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;
 }
 
-- 
2.7.1

             reply	other threads:[~2016-03-09  6:16 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-09  6:16 Matthew Dawson [this message]
2016-03-09  6:16 ` [PATCH] mm/mempool: Avoid KASAN marking mempool posion checks as use-after-free Matthew Dawson
2016-03-10 13:55 ` Andrey Ryabinin
2016-03-10 13:55   ` Andrey Ryabinin

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