linux-kernel - [PATCH] null_blk: oops when initializing without lightnvm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1455198553-24359-1-git-send-email-m@bjorling.me>
Date:	Thu, 11 Feb 2016 14:49:13 +0100
From:	Matias Bjørling <m@...rling.me>
To:	linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
	axboe@...com
Cc:	Matias Bjørling <m@...rling.me>
Subject: [PATCH] null_blk: oops when initializing without lightnvm

If the LightNVM subsystem is not compiled into the kernel, and the
null_blk device driver requests lightnvm to be initialized. The call to
nvm_register fails and the null_add_dev function cleans up the
initialization. However, at this point the null block device has
already been added to the nullb_list and thus a second cleanup will
occur when the function has returned, that leads to a double call to
blk_cleanup_queue.

Signed-off-by: Matias Bjørling <m@...rling.me>
---
 drivers/block/null_blk.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index ae05d31..64a7b59 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -707,9 +707,7 @@ static int null_add_dev(void)
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);
 	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q);
 
-
 	mutex_lock(&lock);
-	list_add_tail(&nullb->list, &nullb_list);
 	nullb->index = nullb_indexes++;
 	mutex_unlock(&lock);
 
@@ -743,6 +741,10 @@ static int null_add_dev(void)
 	strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
 
 	add_disk(disk);
+
+	mutex_lock(&lock);
+	list_add_tail(&nullb->list, &nullb_list);
+	mutex_unlock(&lock);
 done:
 	return 0;
 
-- 
2.1.4