From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Fri, 31 Jan 2020 06:15:07 +0000 (-0800)
Subject: zswap: potential NULL dereference on error in init_zswap()
X-Git-Tag: v5.6-rc1~100^2~44
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=38aeb071b3310866e0e75fec8e5d3c5f0f175cb9;p=linux-2.6-block.git

zswap: potential NULL dereference on error in init_zswap()

The "pool" pointer can be NULL at the end of the init_zswap().  (We
would allocate a new pool later in that situation)

So in the error handling then we need to make sure pool is a valid
pointer before calling "zswap_pool_destroy(pool);" because that function
dereferences the argument.

Link: http://lkml.kernel.org/r/20200114050902.og32fkllkod5ycf5@kili.mountain
Fixes: 93d4dfa9fbd0 ("mm/zswap.c: add allocation hysteresis if pool limit is hit")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/zswap.c b/mm/zswap.c
index 7ec8bd912d13..55094e63b72d 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1359,7 +1359,8 @@ static int __init init_zswap(void)
 	return 0;
 
 fallback_fail:
-	zswap_pool_destroy(pool);
+	if (pool)
+		zswap_pool_destroy(pool);
 hp_fail:
 	cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
 dstmem_fail: