[RFC][PATCH 5/5] mm/zsmalloc: allow NULL `pool' pointer in zs_destroy_pool()

From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Michal Hocko <mhocko@suse.cz>,
	David Rientjes <rientjes@google.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	sergey.senozhatsky.work@gmail.com,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: [RFC][PATCH 5/5] mm/zsmalloc: allow NULL `pool' pointer in zs_destroy_pool()
Date: Tue,  9 Jun 2015 21:04:53 +0900	[thread overview]
Message-ID: <1433851493-23685-6-git-send-email-sergey.senozhatsky@gmail.com> (raw)
In-Reply-To: <1433851493-23685-1-git-send-email-sergey.senozhatsky@gmail.com>

zpool_destroy_pool() does not tolerate a NULL zs_pool pointer
argument and performs a NULL-pointer dereference. Although
there are quite a few zs_destroy_pool() users, still update
it to be coherent with the corresponding destroy() functions
of the remainig pool-allocators (slab, mempool, etc.), which
now allow NULL pool-pointers.

For consistency, tweak zpool_destroy_pool() and NULL-check the
pointer there.

Proposed by Andrew Morton.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Andrew Morton <akpm@linux-foundation.org>
LKML-reference: https://lkml.org/lkml/2015/6/8/583
---
 mm/zsmalloc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index c766240..80964d2 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1868,6 +1868,9 @@ void zs_destroy_pool(struct zs_pool *pool)
 {
 	int i;
 
+	if (unlikely(!pool))
+		return;
+
 	zs_pool_stat_destroy(pool);
 
 	for (i = 0; i < zs_size_classes; i++) {
-- 
2.4.3.368.g7974889

