Patchwork [12/13] ide: Potential null pointer dereference in issue_park_cmd()

login
register
mail settings
Submitter Marina Makienko
Date Aug. 9, 2012, 1:55 p.m.
Message ID <1344520529-19164-10-git-send-email-makienko@ispras.ru>
Download mbox | patch
Permalink /patch/176105/
State Rejected
Delegated to: David Miller
Headers show

Comments

Marina Makienko - Aug. 9, 2012, 1:55 p.m.
The function blk_get_request() can return NULL in some cases. There are
checks on it if function is called with argumetns one of which is
GFP_ATOMIC/GFP_NOIO/etc. If system couldn't find request
blk_get_request() return NULL.

But if there is function call with argument __GFP_WAIT
the system will wait until get request or the queue becomes
dead. If something kills the queue, blk_get_request()
return NULL and next operations will lead to errors.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Marina Makienko <makienko@ispras.ru>
---
 drivers/ide/ide-park.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

Patch

diff --git a/drivers/ide/ide-park.c b/drivers/ide/ide-park.c
index 6ab9ab2..4d178bd 100644
--- a/drivers/ide/ide-park.c
+++ b/drivers/ide/ide-park.c
@@ -32,6 +32,8 @@  static void issue_park_cmd(ide_drive_t *drive, unsigned long timeout)
 	spin_unlock_irq(&hwif->lock);
 
 	rq = blk_get_request(q, READ, __GFP_WAIT);
+	if (!rq)
+		goto out;
 	rq->cmd[0] = REQ_PARK_HEADS;
 	rq->cmd_len = 1;
 	rq->cmd_type = REQ_TYPE_SPECIAL;