From patchwork Thu Aug 9 13:55:29 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [12/13] ide: Potential null pointer dereference in issue_park_cmd() Date: Thu, 09 Aug 2012 03:55:29 -0000 From: Marina Makienko X-Patchwork-Id: 176105 Message-Id: <1344520529-19164-10-git-send-email-makienko@ispras.ru> To: "David S. Miller" Cc: Marina Makienko , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, ldv-project@ispras.ru 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 --- drivers/ide/ide-park.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) 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;