[PATCH 1/2] null_blk: prevent NULL dereference in null_init_tag_set()

From: Dan Carpenter <dan.carpenter@oracle.com>
To: Jens Axboe <axboe@kernel.dk>, Vincent Fu <vincent.fu@samsung.com>
Cc: Chaitanya Kulkarni <kch@nvidia.com>,
	Damien Le Moal <damien.lemoal@opensource.wdc.com>,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>,
	Ming Lei <ming.lei@redhat.com>,
	Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>,
	linux-block@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: [PATCH 1/2] null_blk: prevent NULL dereference in null_init_tag_set()
Date: Fri, 15 Jul 2022 11:10:50 +0300	[thread overview]
Message-ID: <YtEhCjDq2oe2SIkS@kili> (raw)

The "nullb" pointer can be NULL.  Smatch prints a warning about this:

    drivers/block/null_blk/main.c:1914 null_init_tag_set()
    error: we previously assumed 'nullb' could be null (see line 1911)

Fixes: 37ae152c7a0d ("null_blk: add configfs variables for 2 options")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/block/null_blk/main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 67c17e5d2c99..016ec3a2f98f 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1911,9 +1911,9 @@ static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
 	set->numa_node = nullb ? nullb->dev->home_node : g_home_node;
 	set->cmd_size	= sizeof(struct nullb_cmd);
 	set->flags = BLK_MQ_F_SHOULD_MERGE;
-	if (nullb->dev->no_sched)
+	if (nullb && nullb->dev->no_sched)
 		set->flags |= BLK_MQ_F_NO_SCHED;
-	if (nullb->dev->shared_tag_bitmap)
+	if (nullb && nullb->dev->shared_tag_bitmap)
 		set->flags |= BLK_MQ_F_TAG_HCTX_SHARED;
 	set->driver_data = nullb;
 	if (poll_queues)
-- 
2.35.1

