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    Subject[PATCH 12/13] ide: Potential null pointer dereference in issue_park_cmd()
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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-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;
    --
    1.7.7


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