From: Johannes Thumshirn <jthumsh...@suse.de>

Check for a valid direction before starting the request, otherwise we risk
running into an assertion in the scsi midlayer checking for vaild requests.

Signed-off-by: Johannes Thumshirn <jthumsh...@suse.de>
Link: http://www.spinics.net/lists/linux-scsi/msg104400.html
Reported-by: Dmitry Vyukov <dvyu...@google.com>
Reviewed-by: Hannes Reinecke <h...@suse.com>
---
 drivers/scsi/sg.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index c29962c..3599551 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -752,6 +752,20 @@ static int sg_allow_access(struct file *filp, unsigned 
char *cmd)
        return count;
 }
 
+static bool sg_is_valid_direction(int dxfer_direction)
+{
+       switch (dxfer_direction) {
+       case SG_DXFER_NONE:
+       case SG_DXFER_TO_DEV:
+       case SG_DXFER_FROM_DEV:
+       case SG_DXFER_TO_FROM_DEV:
+       case SG_DXFER_UNKNOWN:
+               return true;
+       default:
+               return false;
+       }
+}
+
 static int
 sg_common_write(Sg_fd * sfp, Sg_request * srp,
                unsigned char *cmnd, int timeout, int blocking)
@@ -772,6 +786,11 @@ static int sg_allow_access(struct file *filp, unsigned 
char *cmd)
                        "sg_common_write:  scsi opcode=0x%02x, cmd_size=%d\n",
                        (int) cmnd[0], (int) hp->cmd_len));
 
+       if (!sg_is_valid_direction(hp->dxfer_direction))
+               return -EINVAL;
+       if (hp->dxferp == NULL && hp->dxfer_len > 0)
+               return -EINVAL;
+
        k = sg_start_req(srp, cmnd);
        if (k) {
                SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sfp->parentdp,
-- 
1.8.5.6

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