Messages in this thread Patch in this message | | | From | Marina Makienko <> | Subject | [PATCH 03/13] ide: Potential null pointer dereference in ide_queue_pc_tail() | Date | Thu, 9 Aug 2012 17:55:20 +0400 |
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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-atapi.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/drivers/ide/ide-atapi.c b/drivers/ide/ide-atapi.c index fac3d9d..8bf4109 100644 --- a/drivers/ide/ide-atapi.c +++ b/drivers/ide/ide-atapi.c @@ -93,6 +93,12 @@ int ide_queue_pc_tail(ide_drive_t *drive, struct gendisk *disk, int error; rq = blk_get_request(drive->queue, READ, __GFP_WAIT); + + if (!rq) { + printk(KERN_ERR PFX"ide_queue_pc_tail: blk_get_request() failed. \n"); + return 1; + } + rq->cmd_type = REQ_TYPE_SPECIAL; rq->special = (char *)pc; -- 1.7.7
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