scsi: sg: only check for dxfer_len greater than 256M

commit f930c7043663188429cd9b254e9d761edfc101ce upstream.

Don't make any assumptions on the sg_io_hdr_t::dxfer_direction or the
sg_io_hdr_t::dxferp in order to determine if it is a valid request. The
only way we can check for bad requests is by checking if the length
exceeds 256M.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Fixes: 28676d869bbb (scsi: sg: check for valid direction before starting the request)
Reported-by: Jason L Tibbitts III <tibbs@math.uh.edu>
Tested-by: Jason L Tibbitts III <tibbs@math.uh.edu>
Suggested-by: Doug Gilbert <dgilbert@interlog.com>
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 1f17227..4b43eff 100644 (file)
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -762,35 +762,6 @@ sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf,
        return count;
 }
 
-static bool sg_is_valid_dxfer(sg_io_hdr_t *hp)
-{
-       switch (hp->dxfer_direction) {
-       case SG_DXFER_NONE:
-               if (hp->dxferp || hp->dxfer_len > 0)
-                       return false;
-               return true;
-       case SG_DXFER_FROM_DEV:
-               /*
-                * for SG_DXFER_FROM_DEV we always set dxfer_len to > 0. dxferp
-                * can either be NULL or != NULL so there's no point in checking
-                * it either. So just return true.
-                */
-               return true;
-       case SG_DXFER_TO_DEV:
-       case SG_DXFER_TO_FROM_DEV:
-               if (!hp->dxferp || hp->dxfer_len == 0)
-                       return false;
-               return true;
-       case SG_DXFER_UNKNOWN:
-               if ((!hp->dxferp && hp->dxfer_len) ||
-                   (hp->dxferp && hp->dxfer_len == 0))
-                       return false;
-               return true;
-       default:
-               return false;
-       }
-}
-
 static int
 sg_common_write(Sg_fd * sfp, Sg_request * srp,
                unsigned char *cmnd, int timeout, int blocking)
@@ -811,7 +782,7 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
                        "sg_common_write:  scsi opcode=0x%02x, cmd_size=%d\n",
                        (int) cmnd[0], (int) hp->cmd_len));
 
-       if (!sg_is_valid_dxfer(hp))
+       if (hp->dxfer_len >= SZ_256M)
                return -EINVAL;
 
        k = sg_start_req(srp, cmnd);