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    Subject[PATCH 06/13] ide: Potential null pointer dereference in generic_ide_resume()
    Date
    he 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-pm.c | 6 ++++++
    1 files changed, 6 insertions(+), 0 deletions(-)

    diff --git a/drivers/ide/ide-pm.c b/drivers/ide/ide-pm.c
    index 9240609..4412f24 100644
    --- a/drivers/ide/ide-pm.c
    +++ b/drivers/ide/ide-pm.c
    @@ -19,6 +19,10 @@ int generic_ide_suspend(struct device *dev, pm_message_t mesg)

    memset(&rqpm, 0, sizeof(rqpm));
    rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
    +
    + if (!rq)
    + return -EIO;
    +
    rq->cmd_type = REQ_TYPE_PM_SUSPEND;
    rq->special = &rqpm;
    rqpm.pm_step = IDE_PM_START_SUSPEND;
    @@ -59,6 +63,8 @@ int generic_ide_resume(struct device *dev)

    memset(&rqpm, 0, sizeof(rqpm));
    rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
    + if (!rq)
    + return -EIO;
    rq->cmd_type = REQ_TYPE_PM_RESUME;
    rq->cmd_flags |= REQ_PREEMPT;
    rq->special = &rqpm;
    --
    1.7.7


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