2021-08-10 06:36:53

by Tuo Li

Subject: [PATCH v2] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()

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.

Reported-by: TOTE Robot <[email protected]>
Signed-off-by: Tuo Li <[email protected]>
---
v2:
* Put transport_kunmap_data_sg() into the else-branch of the if (!bug).
Thank Bodo Stroesser for helpful advice.
---
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 2629d2ef3970..75ef52f008ff 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:
--
2.25.1

2021-08-10 08:38:40

by Bodo Stroesser

Subject: Re: [PATCH v2] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()

On 10.08.21 06:04, Tuo Li wrote:
> 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.
>
> Reported-by: TOTE Robot <[email protected]>
> Signed-off-by: Tuo Li <[email protected]>
> ---
> v2:
> * Put transport_kunmap_data_sg() into the else-branch of the if (!bug).
> Thank Bodo Stroesser for helpful advice.
> ---
> 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 2629d2ef3970..75ef52f008ff 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:
>

Reviewed-by: Bodo Stroesser <[email protected]>

Regards,
Bodo

2021-08-17 02:57:00

by Martin K. Petersen

Subject: Re: [PATCH v2] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()

Tuo,

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

Applied to 5.15/scsi-staging, thanks!

--
Martin K. Petersen Oracle Linux Engineering

2021-08-24 04:07:45

by Martin K. Petersen

Subject: Re: [PATCH v2] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()

On Mon, 9 Aug 2021 21:04:13 -0700, Tuo Li wrote:

> 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) {
>
> [...]

Applied to 5.15/scsi-queue, thanks!

[1/1] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()
https://git.kernel.org/mkp/scsi/c/0f99792c01d1

--
Martin K. Petersen Oracle Linux Engineering