From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Date: Tue, 8 Sep 2015 22:00:56 +0000 (-0700)
Subject: mm/dmapool: allow NULL `pool' pointer in dma_pool_destroy()
X-Git-Tag: firefly_0821_release~176^2~1103^2~86
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=44d7175da6ea10e353e69b586bb68bbfef89e403;p=firefly-linux-kernel-4.4.55.git

mm/dmapool: allow NULL `pool' pointer in dma_pool_destroy()

dma_pool_destroy() does not tolerate a NULL dma_pool pointer argument and
performs a NULL-pointer dereference.  This requires additional attention
and effort from developers/reviewers and forces all dma_pool_destroy()
callers to do a NULL check

    if (pool)
        dma_pool_destroy(pool);

Or, otherwise, be invalid dma_pool_destroy() users.

Tweak dma_pool_destroy() and NULL-check the pointer there.

Proposed by Andrew Morton.

Link: https://lkml.org/lkml/2015/6/8/583
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/dmapool.c b/mm/dmapool.c
index 59d10d16f0a5..4b657099111f 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -271,6 +271,9 @@ void dma_pool_destroy(struct dma_pool *pool)
 {
 	bool empty = false;
 
+	if (unlikely(!pool))
+		return;
+
 	mutex_lock(&pools_reg_lock);
 	mutex_lock(&pools_lock);
 	list_del(&pool->pools);