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Subject[PATCH 08/13] ide: Potential null pointer dereference in ide_devset_execute()
Date
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-devsets.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/ide/ide-devsets.c b/drivers/ide/ide-devsets.c
index 9e98122..acdb87f 100644
--- a/drivers/ide/ide-devsets.c
+++ b/drivers/ide/ide-devsets.c
@@ -166,6 +166,8 @@ int ide_devset_execute(ide_drive_t *drive, const struct ide_devset *setting,
return setting->set(drive, arg);

rq = blk_get_request(q, READ, __GFP_WAIT);
+ if (!rq)
+ return -EIO;
rq->cmd_type = REQ_TYPE_SPECIAL;
rq->cmd_len = 5;
rq->cmd[0] = REQ_DEVSET_EXEC;
--
1.7.7


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