Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Tuo Li <islituo@gmail.com>, TOTE Robot <oslab@tsinghua.edu.cn>,
        Bodo Stroesser <bostroesser@gmail.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        Sasha Levin <sashal@kernel.org>, linux-scsi@vger.kernel.org,
        target-devel@vger.kernel.org
Subject: [PATCH AUTOSEL 5.4 18/37] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()
Date:   Thu,  9 Sep 2021 20:21:23 -0400
Message-Id: <20210910002143.175731-18-sashal@kernel.org>
In-Reply-To: <20210910002143.175731-1-sashal@kernel.org>
References: <20210910002143.175731-1-sashal@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Tuo Li <islituo@gmail.com>

[ Upstream commit 0f99792c01d1d6d35b86e850e9ccadd98d6f3e0c ]

The return value of transport_kmap_data_sg() is assigned to the variable
buf:

  buf = transport_kmap_data_sg(cmd);

And then it is checked:

  if (!buf) {

This indicates that buf can be NULL. However, it is dereferenced in the
following statements:

  if (!(buf[3] & 0x80))
    buf[3] |= 0x80;
  if (!(buf[2] & 0x80))
    buf[2] |= 0x80;

To fix these possible null-pointer dereferences, dereference buf and call
transport_kunmap_data_sg() only when buf is not NULL.

Link: https://lore.kernel.org/r/20210810040414.248167-1-islituo@gmail.com
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Reviewed-by: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Tuo Li <islituo@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/target/target_core_pscsi.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 55fe93296deb..17811bb07e9f 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -622,17 +622,17 @@ static void pscsi_complete_cmd(struct se_cmd *cmd, u8 scsi_status,
 			buf = transport_kmap_data_sg(cmd);
 			if (!buf) {
 				; /* XXX: TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE */
-			}
-
-			if (cdb[0] == MODE_SENSE_10) {
-				if (!(buf[3] & 0x80))
-					buf[3] |= 0x80;
 			} else {
-				if (!(buf[2] & 0x80))
-					buf[2] |= 0x80;
-			}
+				if (cdb[0] == MODE_SENSE_10) {
+					if (!(buf[3] & 0x80))
+						buf[3] |= 0x80;
+				} else {
+					if (!(buf[2] & 0x80))
+						buf[2] |= 0x80;
+				}
 
-			transport_kunmap_data_sg(cmd);
+				transport_kunmap_data_sg(cmd);
+			}
 		}
 	}
 after_mode_sense:
-- 
2.30.2