From: Mikulas Patocka <mpatocka@redhat.com>
Date: Tue, 18 Apr 2023 15:57:47 -0400
Subject: [PATCH] dm flakey: fix a crash with invalid table line
References: bsc#1012628
Patch-mainline: 6.3.2
Git-commit: 98dba02d9a93eec11bffbb93c7c51624290702d2

commit 98dba02d9a93eec11bffbb93c7c51624290702d2 upstream.

This command will crash with NULL pointer dereference:
 dmsetup create flakey --table \
  "0 `blockdev --getsize /dev/ram0` flakey /dev/ram0 0 0 1 2 corrupt_bio_byte 512"

Fix the crash by checking if arg_name is non-NULL before comparing it.

Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/md/dm-flakey.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index 5b7556d2..468d0253 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -125,9 +125,9 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
 			 * Direction r or w?
 			 */
 			arg_name = dm_shift_arg(as);
-			if (!strcasecmp(arg_name, "w"))
+			if (arg_name && !strcasecmp(arg_name, "w"))
 				fc->corrupt_bio_rw = WRITE;
-			else if (!strcasecmp(arg_name, "r"))
+			else if (arg_name && !strcasecmp(arg_name, "r"))
 				fc->corrupt_bio_rw = READ;
 			else {
 				ti->error = "Invalid corrupt bio direction (r or w)";
-- 
2.35.3