* [PATCH] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()
@ 2021-08-07 13:46 Tuo Li
2021-08-09 10:36 ` Bodo Stroesser
0 siblings, 1 reply; 3+ messages in thread
From: Tuo Li @ 2021-08-07 13:46 UTC (permalink / raw)
To: martin.petersen
Cc: linux-scsi, target-devel, linux-kernel, baijiaju1990, Tuo Li,
TOTE Robot
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 only when
it is not NULL.
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
---
drivers/target/target_core_pscsi.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 2629d2ef3970..560815729182 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -620,14 +620,14 @@ 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);
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()
2021-08-07 13:46 [PATCH] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd() Tuo Li
@ 2021-08-09 10:36 ` Bodo Stroesser
2021-08-09 11:50 ` Tuo Li
0 siblings, 1 reply; 3+ messages in thread
From: Bodo Stroesser @ 2021-08-09 10:36 UTC (permalink / raw)
To: Tuo Li, martin.petersen
Cc: linux-scsi, target-devel, linux-kernel, baijiaju1990, TOTE Robot
On 07.08.21 15:46, 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 only when
> it is not NULL.
>
> Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
> Signed-off-by: Tuo Li <islituo@gmail.com>
> ---
> drivers/target/target_core_pscsi.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
> index 2629d2ef3970..560815729182 100644
> --- a/drivers/target/target_core_pscsi.c
> +++ b/drivers/target/target_core_pscsi.c
> @@ -620,14 +620,14 @@ 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);
>
I'm wondering whether we should better put the
transport_kunmap_data_sg into the else-branch of the if (!buf)?
AFAICS, calling it after transport_kmap_data_sg failed does not
cause problems, but I feel it would be cleaner.
Otherwise it looks good to me.
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()
2021-08-09 10:36 ` Bodo Stroesser
@ 2021-08-09 11:50 ` Tuo Li
0 siblings, 0 replies; 3+ messages in thread
From: Tuo Li @ 2021-08-09 11:50 UTC (permalink / raw)
To: Bodo Stroesser
Cc: linux-scsi, target-devel, linux-kernel, baijiaju1990, TOTE Robot,
martin.petersen
Thanks for your feedback. We will prepare a V2 patch and put the
transport_kunmap_data_sg()
into the else-branch of the if (!buf).
Best wishes,
Tuo Li
On 2021/8/9 18:36, Bodo Stroesser wrote:
> On 07.08.21 15:46, 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 only
>> when
>> it is not NULL.
>>
>> Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
>> Signed-off-by: Tuo Li <islituo@gmail.com>
>> ---
>> drivers/target/target_core_pscsi.c | 14 +++++++-------
>> 1 file changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/target/target_core_pscsi.c
>> b/drivers/target/target_core_pscsi.c
>> index 2629d2ef3970..560815729182 100644
>> --- a/drivers/target/target_core_pscsi.c
>> +++ b/drivers/target/target_core_pscsi.c
>> @@ -620,14 +620,14 @@ 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);
>>
>
> I'm wondering whether we should better put the
> transport_kunmap_data_sg into the else-branch of the if (!buf)?
> AFAICS, calling it after transport_kmap_data_sg failed does not
> cause problems, but I feel it would be cleaner.
>
> Otherwise it looks good to me.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-08-07 13:46 [PATCH] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd() Tuo Li
2021-08-09 10:36 ` Bodo Stroesser
2021-08-09 11:50 ` Tuo Li
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