From: Johannes Thumshirn <jthumshirn@suse.de>
Date: Fri, 7 Jul 2017 08:56:38 +0000 (+0200)
Subject: scsi: sg: fix SG_DXFER_FROM_DEV transfers
X-Git-Tag: v3.18.101~3
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=103660de0e4769e5d3d59395044fa698e55d21d3;p=linux

scsi: sg: fix SG_DXFER_FROM_DEV transfers

commit 68c59fcea1f2c6a54c62aa896cc623c1b5bc9b47 upstream.

SG_DXFER_FROM_DEV transfers do not necessarily have a dxferp as we set
it to NULL for the old sg_io read/write interface, but must have a
length bigger than 0. This fixes a regression introduced by commit
28676d869bbb ("scsi: sg: check for valid direction before starting the
request")

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Fixes: 28676d869bbb ("scsi: sg: check for valid direction before starting the request")
Reported-by: Chris Clayton <chris2553@googlemail.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Cristian Crinteanu <crinteanu.cristian@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index cab426720144..d344bc652a8f 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -769,8 +769,11 @@ static bool sg_is_valid_dxfer(sg_io_hdr_t *hp)
 		if (hp->dxferp || hp->dxfer_len > 0)
 			return false;
 		return true;
-	case SG_DXFER_TO_DEV:
 	case SG_DXFER_FROM_DEV:
+		if (hp->dxfer_len < 0)
+			return false;
+		return true;
+	case SG_DXFER_TO_DEV:
 	case SG_DXFER_TO_FROM_DEV:
 		if (!hp->dxferp || hp->dxfer_len == 0)
 			return false;