Re: [PATCH v2] Staging: rtl8723bs: Check sscanf return value

[Georgiana Chelu <georgiana.chelu93@gmail.com>]

On 18 October 2017 at 17:03, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> On Wed, Oct 18, 2017 at 12:39:11AM +0300, Georgiana Chelu wrote:
>> Check the sscanf return value and handle it. The function returns
>> the number of items of the argument list successfully filled.
>>
>> Issue found by checkpatch.pl.
>> WARNING: unchecked sscanf return value
>>
>> Signed-off-by: Georgiana Chelu <georgiana.chelu93@gmail.com>
>> ---
>>
>> Changes in v2:
>> * compared the return value of scanf to the right value
>> * improved the commit message
>>
>>  drivers/staging/rtl8723bs/os_dep/ioctl_linux.c | 11 +++++++++--
>>  1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
>> index 3fca0c2d4c8d..fe538cc088f0 100644
>> --- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
>> +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
>> @@ -2356,7 +2356,11 @@ static int rtw_wx_read32(struct net_device *dev,
>>
>>       bytes = 0;
>>       addr = 0;
>> -     sscanf(ptmp, "%d,%x", &bytes, &addr);
>> +     ret = sscanf(ptmp, "%d,%x", &bytes, &addr);
>> +     if (ret != 2) {
>> +             ret = -EINVAL;
>> +             goto exit;
>> +     }
>
> Are you sure that the code requires 2 values here?
>
>>
>>       switch (bytes) {
>>               case 1:
>> @@ -2393,12 +2397,15 @@ static int rtw_wx_write32(struct net_device *dev,
>>       u32 addr;
>>       u32 data32;
>>       u32 bytes;
>> +     int ret;
>>
>>
>>       bytes = 0;
>>       addr = 0;
>>       data32 = 0;
>> -     sscanf(extra, "%d,%x,%x", &bytes, &addr, &data32);xbytes, &addr, &data32);
>> +     if (ret != 3)
>> +             return -EINVAL;
>
> Same here, are you sure that 3 values are required?
>

I think I understand what you are saying. The 'addr' and 'data32'
could be 0 because one can write 0 bytes at the starting address of
the 'padapter' structure. Also, the switch statement handles the case
when 'bytes' does not have one of the expected values.

Please, tell me if I understood correctly.


Thanks,
Georgiana


> thanks,
>
> greg k-h