[PATCH AUTOSEL 5.13 43/88] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()

Sasha Levin
2021-09-10T00:50:57Z

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 f2a11414366d..da5de58bd3bb 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -620,17 +620,17 @@ 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