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    Subject[PATCH 05/13] ide: Potential null pointer dereference in ide_raw_taskfile()
    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-taskfile.c | 4 ++++
    1 files changed, 4 insertions(+), 0 deletions(-)

    diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
    index 729428e..655d894 100644
    --- a/drivers/ide/ide-taskfile.c
    +++ b/drivers/ide/ide-taskfile.c
    @@ -432,6 +432,10 @@ int ide_raw_taskfile(ide_drive_t *drive, struct ide_cmd *cmd, u8 *buf,
    int rw = !(cmd->tf_flags & IDE_TFLAG_WRITE) ? READ : WRITE;

    rq = blk_get_request(drive->queue, rw, __GFP_WAIT);
    +
    + if (!rq)
    + return -EIO;
    +
    rq->cmd_type = REQ_TYPE_ATA_TASKFILE;

    /*
    --
    1.7.7


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