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    Subject[PATCH 10/13] ide: Potential null pointer dereference in ide_cd_queue_pc()
    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-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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