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    Subject[PATCH 4.12 070/196] usb: storage: return on error to avoid a null pointer dereference
    Date
    4.12-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Colin Ian King <colin.king@canonical.com>

    commit 446230f52a5bef593554510302465eabab45a372 upstream.

    When us->extra is null the driver is not initialized, however, a
    later call to osd200_scsi_to_ata is made that dereferences
    us->extra, causing a null pointer dereference. The code
    currently detects and reports that the driver is not initialized;
    add a return to avoid the subsequent dereference issue in this
    check.

    Thanks to Alan Stern for pointing out that srb->result needs setting
    to DID_ERROR << 16

    Detected by CoverityScan, CID#100308 ("Dereference after null check")

    Signed-off-by: Colin Ian King <colin.king@canonical.com>
    Acked-by: Alan Stern <stern@rowland.harvard.edu>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/usb/storage/isd200.c | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    --- a/drivers/usb/storage/isd200.c
    +++ b/drivers/usb/storage/isd200.c
    @@ -1529,8 +1529,11 @@ static void isd200_ata_command(struct sc

    /* Make sure driver was initialized */

    - if (us->extra == NULL)
    + if (us->extra == NULL) {
    usb_stor_dbg(us, "ERROR Driver not initialized\n");
    + srb->result = DID_ERROR << 16;
    + return;
    + }

    scsi_set_resid(srb, 0);
    /* scsi_bufflen might change in protocol translation to ata */

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