Re: [PATCH v2] scsi/cxgbi/libcxgbi: make sure sg is present before calling sg_next()

Re: [PATCH v2] scsi/cxgbi/libcxgbi: make sure sg is present before calling sg_next()

[Mike Christie]

On 11/14/22 9:09 AM, Daniil Tatianin wrote:
> sg_next() dereferences the passed sg, therefore we have to verify that
> it's present before calling it.
> 
> Found by Linux Verification Center (linuxtesting.org) with the SVACE
> static analysis tool.
> 
> Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
> ---
>  drivers/scsi/cxgbi/libcxgbi.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/cxgbi/libcxgbi.c b/drivers/scsi/cxgbi/libcxgbi.c
> index af281e271f88..2ff9810f42a9 100644
> --- a/drivers/scsi/cxgbi/libcxgbi.c
> +++ b/drivers/scsi/cxgbi/libcxgbi.c
> @@ -1196,8 +1196,7 @@ void cxgbi_ddp_set_one_ppod(struct cxgbi_pagepod *ppod,
>  
>  	if (offset == len) {
>  		offset = 0;
> -		sg = sg_next(sg);
> -		if (sg) {
> +		if (sg && (sg = sg_next(sg))) {
>  			addr = sg_dma_address(sg);
>  			len = sg_dma_len(sg);
>  		}

Is cxgbit_set_one_ppod the same function but it already has the extra
sg check? Should it be a libcxgb function in libcxgb_ppm.c?

Re: [PATCH v2] scsi/cxgbi/libcxgbi: make sure sg is present before calling sg_next()

[Mike Christie]

Cc'ing the cxgbi/t maintainer, Varun.

On 11/15/22 2:17 AM, Daniil Tatianin wrote:
> On 11/15/22 1:23 AM, Mike Christie wrote:
>> On 11/14/22 9:09 AM, Daniil Tatianin wrote:
>>> sg_next() dereferences the passed sg, therefore we have to verify that
>>> it's present before calling it.
>>>
>>> Found by Linux Verification Center (linuxtesting.org) with the SVACE
>>> static analysis tool.
>>>
>>> Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
>>> ---
>>>   drivers/scsi/cxgbi/libcxgbi.c | 3 +--
>>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/scsi/cxgbi/libcxgbi.c b/drivers/scsi/cxgbi/libcxgbi.c
>>> index af281e271f88..2ff9810f42a9 100644
>>> --- a/drivers/scsi/cxgbi/libcxgbi.c
>>> +++ b/drivers/scsi/cxgbi/libcxgbi.c
>>> @@ -1196,8 +1196,7 @@ void cxgbi_ddp_set_one_ppod(struct cxgbi_pagepod *ppod,
>>>         if (offset == len) {
>>>           offset = 0;
>>> -        sg = sg_next(sg);
>>> -        if (sg) {
>>> +        if (sg && (sg = sg_next(sg))) {
>>>               addr = sg_dma_address(sg);
>>>               len = sg_dma_len(sg);
>>>           }
>>
>> Is cxgbit_set_one_ppod the same function but it already has the extra
>> sg check?
> 
> Good catch! Certainly looks that way, albeit with messier indentation.
> 
>> Should it be a libcxgb function in libcxgb_ppm.c?
> 
> That makes sense to me. Should I just move both there?

I think you can move one function with a fix to libcxgb and kill the second one.
Name the new function to cxgb_ddp_set_one_ppod then have cxgbi and cxgbt use it.

RE: [PATCH v2] scsi/cxgbi/libcxgbi: make sure sg is present before calling sg_next()

[Varun Prakash]

>>>>> diff --git a/drivers/scsi/cxgbi/libcxgbi.c 
>>>>> b/drivers/scsi/cxgbi/libcxgbi.c index af281e271f88..2ff9810f42a9 
>>>>> 100644
>>>>> --- a/drivers/scsi/cxgbi/libcxgbi.c
>>>>> +++ b/drivers/scsi/cxgbi/libcxgbi.c
>>>>> @@ -1196,8 +1196,7 @@ void cxgbi_ddp_set_one_ppod(struct 
>>>>> cxgbi_pagepod *ppod,
>>>>>          if (offset == len) {
>>>>>            offset = 0;
>>>>> -        sg = sg_next(sg);
>>>>> -        if (sg) {
>>>>> +        if (sg && (sg = sg_next(sg))) {
>>>>>                addr = sg_dma_address(sg);
>>>>>                len = sg_dma_len(sg);
>>>>>            }
>>>>
>>>> Is cxgbit_set_one_ppod the same function but it already has the 
>>>> extra sg check?
>>>
>>> Good catch! Certainly looks that way, albeit with messier indentation.
>>>
>>>> Should it be a libcxgb function in libcxgb_ppm.c?
>>>
>>> That makes sense to me. Should I just move both there?
>> 
>> I think you can move one function with a fix to libcxgb and kill the second one.
>> Name the new function to cxgb_ddp_set_one_ppod then have cxgbi and cxgbt use it.
>
>Yeah, thah's pretty much what I meant. Thank you!

Yes, you can move cxgbit_set_one_ppod() from cxgbit_ddp.c to libcxgb_ppm.c and
rename it to cxgbi_ppm_set_one_ppod() and remove cxgbi_ddp_set_one_ppod()
from libcxgbi.c.