linux-kernel - [PATCH] scsi: sg: fix static checker warning in sg_is_valid

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Message-Id: <20170717131142.14069-1-jthumshirn@suse.de>
Date:   Mon, 17 Jul 2017 15:11:42 +0200
From:   Johannes Thumshirn <jthumshirn@...e.de>
To:     "Martin K . Petersen" <martin.petersen@...cle.com>
Cc:     Linux SCSI Mailinglist <linux-scsi@...r.kernel.org>,
        Linux Kernel Mailinglist <linux-kernel@...r.kernel.org>,
        Colin Ian King <colin.king@...onical.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        Douglas Gilbert <dgilbert@...erlog.com>
Subject: [PATCH] scsi: sg: fix static checker warning in sg_is_valid_dxfer

dxfer_len is an unsigned int and we always assign a value > 0 to it, so it
doesn't make any sense to check if it is < 0. We can't really check dxferp as
well as we have both NULL and not NULL cases in the possible call paths.

So just return true for SG_DXFER_FROM_DEV transfer in sg_is_valid_dxfer().

Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
Reported-by: Colin Ian King <colin.king@...onical.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Cc: Douglas Gilbert <dgilbert@...erlog.com>
---
 drivers/scsi/sg.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 1e82d4128a84..4fe606b000b4 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -759,8 +759,11 @@ static bool sg_is_valid_dxfer(sg_io_hdr_t *hp)
 			return false;
 		return true;
 	case SG_DXFER_FROM_DEV:
-		if (hp->dxfer_len < 0)
-			return false;
+		/*
+		 * 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:
-- 
2.12.3