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Subject[PATCH 10/13] ide: Potential null pointer dereference in ide_cd_queue_pc()
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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-cd.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 8126824..9dd575d 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -443,6 +443,9 @@ int ide_cd_queue_pc(ide_drive_t *drive, const unsigned char *cmd,

rq = blk_get_request(drive->queue, write, __GFP_WAIT);

+ if (!rq)
+ return -EIO;
+
memcpy(rq->cmd, cmd, BLK_MAX_CDB);
rq->cmd_type = REQ_TYPE_ATA_PC;
rq->sense = sense;
--
1.7.7


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