staging: gpib: Move free after the variable use has been completed

[PATCH] staging: gpib: Move free after the variable use has been completed

Posted by Everest K.C. 1 month, 1 week ago

The variable `in_data` is freed, but used later in the code.
Fix it by moving the freeing the memory after it use has been
completed.

This issue was reported by Coverity Scan.
Report:
CID 1600783: (#1 of 1): Use after free (USE_AFTER_FREE)
19. pass_freed_arg: Passing freed pointer in_data as an argument to
ni_usb_dump_raw_block.

Fixes: 4e127de14fa7 ("staging: gpib: Add National Instruments USB GPIB driver")
Signed-off-by: Everest K.C. <everestkc@everestkc.com.np>
---
 drivers/staging/gpib/ni_usb/ni_usb_gpib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
index 1da263676f2a..75f39e1f3ed1 100644
--- a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
+++ b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
@@ -690,12 +690,12 @@ static int ni_usb_read(gpib_board_t *board, uint8_t *buffer, size_t length,
 		kfree(in_data);
 		return parse_retval;
 	}
-	kfree(in_data);
 	if (actual_length != length - status.count) {
 		pr_err("%s: actual_length=%i expected=%li\n",
 		       __func__, actual_length, (long)(length - status.count));
 		ni_usb_dump_raw_block(in_data, usb_bytes_read);
 	}
+	kfree(in_data);
 	switch (status.error_code) {
 	case NIUSB_NO_ERROR:
 		retval = 0;
-- 
2.43.0

Re: [PATCH] staging: gpib: Move free after the variable use has been completed

Posted by Shuah Khan 1 month, 1 week ago

On 10/15/24 15:51, Everest K.C. wrote:
> The variable `in_data` is freed, but used later in the code.
> Fix it by moving the freeing the memory after it use has been
> completed.
> 
> This issue was reported by Coverity Scan.
> Report:
> CID 1600783: (#1 of 1): Use after free (USE_AFTER_FREE)
> 19. pass_freed_arg: Passing freed pointer in_data as an argument to
> ni_usb_dump_raw_block.
> 
> Fixes: 4e127de14fa7 ("staging: gpib: Add National Instruments USB GPIB driver")
> Signed-off-by: Everest K.C. <everestkc@everestkc.com.np>
> ---
>   drivers/staging/gpib/ni_usb/ni_usb_gpib.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
> index 1da263676f2a..75f39e1f3ed1 100644
> --- a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
> +++ b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
> @@ -690,12 +690,12 @@ static int ni_usb_read(gpib_board_t *board, uint8_t *buffer, size_t length,
>   		kfree(in_data);
>   		return parse_retval;
>   	}
> -	kfree(in_data);
>   	if (actual_length != length - status.count) {
>   		pr_err("%s: actual_length=%i expected=%li\n",
>   		       __func__, actual_length, (long)(length - status.count));
>   		ni_usb_dump_raw_block(in_data, usb_bytes_read);
>   	}
> +	kfree(in_data);
>   	switch (status.error_code) {
>   	case NIUSB_NO_ERROR:
>   		retval = 0;

Looks good to me. Isn't this on next though. Don't forget to
indicate it is against next.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah

Re: [PATCH] staging: gpib: Move free after the variable use has been completed

Posted by Everest K.C. 1 month, 1 week ago

On Tue, Oct 15, 2024 at 4:35 PM Shuah Khan <skhan@linuxfoundation.org> wrote:
>
> On 10/15/24 15:51, Everest K.C. wrote:
> > The variable `in_data` is freed, but used later in the code.
> > Fix it by moving the freeing the memory after it use has been
> > completed.
> >
> > This issue was reported by Coverity Scan.
> > Report:
> > CID 1600783: (#1 of 1): Use after free (USE_AFTER_FREE)
> > 19. pass_freed_arg: Passing freed pointer in_data as an argument to
> > ni_usb_dump_raw_block.
> >
> > Fixes: 4e127de14fa7 ("staging: gpib: Add National Instruments USB GPIB driver")
> > Signed-off-by: Everest K.C. <everestkc@everestkc.com.np>
> > ---
> >   drivers/staging/gpib/ni_usb/ni_usb_gpib.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
> > index 1da263676f2a..75f39e1f3ed1 100644
> > --- a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
> > +++ b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
> > @@ -690,12 +690,12 @@ static int ni_usb_read(gpib_board_t *board, uint8_t *buffer, size_t length,
> >               kfree(in_data);
> >               return parse_retval;
> >       }
> > -     kfree(in_data);
> >       if (actual_length != length - status.count) {
> >               pr_err("%s: actual_length=%i expected=%li\n",
> >                      __func__, actual_length, (long)(length - status.count));
> >               ni_usb_dump_raw_block(in_data, usb_bytes_read);
> >       }
> > +     kfree(in_data);
> >       switch (status.error_code) {
> >       case NIUSB_NO_ERROR:
> >               retval = 0;
>
> Looks good to me. Isn't this on next though. Don't forget to
> indicate it is against next.
No, it was fixed in the linux-staging repo.
> Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
>
> thanks,
> -- Shuah

Re: [PATCH] staging: gpib: Move free after the variable use has been completed

Posted by Shuah Khan 1 month, 1 week ago

On 10/15/24 16:48, Everest K.C. wrote:
> On Tue, Oct 15, 2024 at 4:35 PM Shuah Khan <skhan@linuxfoundation.org> wrote:
>>
>> On 10/15/24 15:51, Everest K.C. wrote:
>>> The variable `in_data` is freed, but used later in the code.
>>> Fix it by moving the freeing the memory after it use has been
>>> completed.
>>>
>>> This issue was reported by Coverity Scan.
>>> Report:
>>> CID 1600783: (#1 of 1): Use after free (USE_AFTER_FREE)
>>> 19. pass_freed_arg: Passing freed pointer in_data as an argument to
>>> ni_usb_dump_raw_block.
>>>
>>> Fixes: 4e127de14fa7 ("staging: gpib: Add National Instruments USB GPIB driver")
>>> Signed-off-by: Everest K.C. <everestkc@everestkc.com.np>
>>> ---
>>>    drivers/staging/gpib/ni_usb/ni_usb_gpib.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
>>> index 1da263676f2a..75f39e1f3ed1 100644
>>> --- a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
>>> +++ b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
>>> @@ -690,12 +690,12 @@ static int ni_usb_read(gpib_board_t *board, uint8_t *buffer, size_t length,
>>>                kfree(in_data);
>>>                return parse_retval;
>>>        }
>>> -     kfree(in_data);
>>>        if (actual_length != length - status.count) {
>>>                pr_err("%s: actual_length=%i expected=%li\n",
>>>                       __func__, actual_length, (long)(length - status.count));
>>>                ni_usb_dump_raw_block(in_data, usb_bytes_read);
>>>        }
>>> +     kfree(in_data);
>>>        switch (status.error_code) {
>>>        case NIUSB_NO_ERROR:
>>>                retval = 0;
>>
>> Looks good to me. Isn't this on next though. Don't forget to
>> indicate it is against next.
> No, it was fixed in the linux-staging repo.
>> Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
>>

Okay - by the way the same problem is in ni_usb_write_registers().
Did coverity catch that one?

Both problems could be fix in one patch - I will leave it up to the
maintainers to make a call on two patches or a single patch.

thanks,
-- Shuah

Re: [PATCH] staging: gpib: Move free after the variable use has been completed

Posted by Everest K.C. 1 month, 1 week ago

On Tue, Oct 15, 2024 at 4:55 PM Shuah Khan <skhan@linuxfoundation.org> wrote:
>
> On 10/15/24 16:48, Everest K.C. wrote:
> > On Tue, Oct 15, 2024 at 4:35 PM Shuah Khan <skhan@linuxfoundation.org> wrote:
> >>
> >> On 10/15/24 15:51, Everest K.C. wrote:
> >>> The variable `in_data` is freed, but used later in the code.
> >>> Fix it by moving the freeing the memory after it use has been
> >>> completed.
> >>>
> >>> This issue was reported by Coverity Scan.
> >>> Report:
> >>> CID 1600783: (#1 of 1): Use after free (USE_AFTER_FREE)
> >>> 19. pass_freed_arg: Passing freed pointer in_data as an argument to
> >>> ni_usb_dump_raw_block.
> >>>
> >>> Fixes: 4e127de14fa7 ("staging: gpib: Add National Instruments USB GPIB driver")
> >>> Signed-off-by: Everest K.C. <everestkc@everestkc.com.np>
> >>> ---
> >>>    drivers/staging/gpib/ni_usb/ni_usb_gpib.c | 2 +-
> >>>    1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
> >>> index 1da263676f2a..75f39e1f3ed1 100644
> >>> --- a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
> >>> +++ b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
> >>> @@ -690,12 +690,12 @@ static int ni_usb_read(gpib_board_t *board, uint8_t *buffer, size_t length,
> >>>                kfree(in_data);
> >>>                return parse_retval;
> >>>        }
> >>> -     kfree(in_data);
> >>>        if (actual_length != length - status.count) {
> >>>                pr_err("%s: actual_length=%i expected=%li\n",
> >>>                       __func__, actual_length, (long)(length - status.count));
> >>>                ni_usb_dump_raw_block(in_data, usb_bytes_read);
> >>>        }
> >>> +     kfree(in_data);
> >>>        switch (status.error_code) {
> >>>        case NIUSB_NO_ERROR:
> >>>                retval = 0;
> >>
> >> Looks good to me. Isn't this on next though. Don't forget to
> >> indicate it is against next.
> > No, it was fixed in the linux-staging repo.
> >> Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
> >>
>
> Okay - by the way the same problem is in ni_usb_write_registers().
> Did coverity catch that one?
No, there were no similar issues caught by coverity.
Also, I just checked the function. I didn't see the variable being
accessed after
it had been freed.
> Both problems could be fix in one patch - I will leave it up to the
> maintainers to make a call on two patches or a single patch.
>
> thanks,
> -- Shuah
>

Re: [PATCH] staging: gpib: Move free after the variable use has been completed

Posted by Shuah Khan 1 month, 1 week ago

On 10/15/24 17:04, Everest K.C. wrote:
> On Tue, Oct 15, 2024 at 4:55 PM Shuah Khan <skhan@linuxfoundation.org> wrote:
>>
>> On 10/15/24 16:48, Everest K.C. wrote:
>>> On Tue, Oct 15, 2024 at 4:35 PM Shuah Khan <skhan@linuxfoundation.org> wrote:
>>>>
>>>> On 10/15/24 15:51, Everest K.C. wrote:
>>>>> The variable `in_data` is freed, but used later in the code.
>>>>> Fix it by moving the freeing the memory after it use has been
>>>>> completed.
>>>>>
>>>>> This issue was reported by Coverity Scan.
>>>>> Report:
>>>>> CID 1600783: (#1 of 1): Use after free (USE_AFTER_FREE)
>>>>> 19. pass_freed_arg: Passing freed pointer in_data as an argument to
>>>>> ni_usb_dump_raw_block.
>>>>>
>>>>> Fixes: 4e127de14fa7 ("staging: gpib: Add National Instruments USB GPIB driver")
>>>>> Signed-off-by: Everest K.C. <everestkc@everestkc.com.np>
>>>>> ---
>>>>>     drivers/staging/gpib/ni_usb/ni_usb_gpib.c | 2 +-
>>>>>     1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
>>>>> index 1da263676f2a..75f39e1f3ed1 100644
>>>>> --- a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
>>>>> +++ b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
>>>>> @@ -690,12 +690,12 @@ static int ni_usb_read(gpib_board_t *board, uint8_t *buffer, size_t length,
>>>>>                 kfree(in_data);
>>>>>                 return parse_retval;
>>>>>         }
>>>>> -     kfree(in_data);
>>>>>         if (actual_length != length - status.count) {
>>>>>                 pr_err("%s: actual_length=%i expected=%li\n",
>>>>>                        __func__, actual_length, (long)(length - status.count));
>>>>>                 ni_usb_dump_raw_block(in_data, usb_bytes_read);
>>>>>         }
>>>>> +     kfree(in_data);
>>>>>         switch (status.error_code) {
>>>>>         case NIUSB_NO_ERROR:
>>>>>                 retval = 0;
>>>>
>>>> Looks good to me. Isn't this on next though. Don't forget to
>>>> indicate it is against next.
>>> No, it was fixed in the linux-staging repo.
>>>> Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
>>>>
>>
>> Okay - by the way the same problem is in ni_usb_write_registers().
>> Did coverity catch that one?
> No, there were no similar issues caught by coverity.
> Also, I just checked the function. I didn't see the variable being
> accessed after
> it had been freed.

Yeah. You are right. It was out_data that was freed after
last access. in_data is fine.

thanks,
-- Shuah