Re: drivers/staging/rtl8723bs/core/rtw_security.c:95:9: warning: variable 'crc' set but not used

[Rong Chen <rong.a.chen@intel.com>]

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On 6/21/21 3:50 AM, Jhih Ming Huang wrote:
> On Sat, Jun 19, 2021 at 6:27 PM kernel test robot <lkp@intel.com> wrote:
>> tree:   https://github.com/0day-ci/linux/commits/UPDATE-20210619-155350/Jhih-Ming-Huang/rtw_security-fix-cast-to-restricted-__le32/20210616-131056
>> head:   ed0359e3fa64928e48021387a694f211bc840ff7
>> commit: ed0359e3fa64928e48021387a694f211bc840ff7 rtw_security: fix cast to restricted __le32
>> date:   3 hours ago
>> config: sh-allmodconfig (attached as .config)
>> compiler: sh4-linux-gcc (GCC) 9.3.0
>> reproduce (this is a W=1 build):
>>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>          chmod +x ~/bin/make.cross
>>          # https://github.com/0day-ci/linux/commit/ed0359e3fa64928e48021387a694f211bc840ff7
>>          git remote add linux-review https://github.com/0day-ci/linux
>>          git fetch --no-tags linux-review UPDATE-20210619-155350/Jhih-Ming-Huang/rtw_security-fix-cast-to-restricted-__le32/20210616-131056
>>          git checkout ed0359e3fa64928e48021387a694f211bc840ff7
>>          # save the attached .config to linux build tree
>>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=sh
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@intel.com>
>>
>> All warnings (new ones prefixed by >>):
>>
>>     drivers/staging/rtl8723bs/core/rtw_security.c: In function 'rtw_wep_decrypt':
>>>> drivers/staging/rtl8723bs/core/rtw_security.c:95:9: warning: variable 'crc' set but not used [-Wunused-but-set-variable]
>>        95 |  __le32 crc;
>>           |         ^~~
>>
>> Kconfig warnings: (for reference only)
>>     WARNING: unmet direct dependencies detected for SND_ATMEL_SOC_PDC
>>     Depends on SOUND && !UML && SND && SND_SOC && SND_ATMEL_SOC && HAS_DMA
>>     Selected by
>>     - SND_ATMEL_SOC_SSC && SOUND && !UML && SND && SND_SOC && SND_ATMEL_SOC
>>     - SND_ATMEL_SOC_SSC_PDC && SOUND && !UML && SND && SND_SOC && SND_ATMEL_SOC && ATMEL_SSC
>>
>>
>> vim +/crc +95 drivers/staging/rtl8723bs/core/rtw_security.c
>>
>>      91
>>      92  void rtw_wep_decrypt(struct adapter  *padapter, u8 *precvframe)
>>      93  {
>>      94          /*  exclude ICV */
>>    > 95          __le32 crc;
>>      96          signed int      length;
>>      97          u32 keylength;
>>      98          u8 *pframe, *payload, *iv, wepkey[16];
>>      99          u8  keyindex;
>>     100          struct  rx_pkt_attrib    *prxattrib = &(((union recv_frame *)precvframe)->u.hdr.attrib);
>>     101          struct  security_priv *psecuritypriv = &padapter->securitypriv;
>>     102          struct arc4_ctx *ctx = &psecuritypriv->recv_arc4_ctx;
>>     103
>>     104          pframe = (unsigned char *)((union recv_frame *)precvframe)->u.hdr.rx_data;
>>     105
>>     106          /* start to decrypt recvframe */
>>     107          if ((prxattrib->encrypt == _WEP40_) || (prxattrib->encrypt == _WEP104_)) {
>>     108                  iv = pframe+prxattrib->hdrlen;
>>     109                  /* keyindex =(iv[3]&0x3); */
>>     110                  keyindex = prxattrib->key_index;
>>     111                  keylength = psecuritypriv->dot11DefKeylen[keyindex];
>>     112                  memcpy(&wepkey[0], iv, 3);
>>     113                  /* memcpy(&wepkey[3], &psecuritypriv->dot11DefKey[psecuritypriv->dot11PrivacyKeyIndex].skey[0], keylength); */
>>     114                  memcpy(&wepkey[3], &psecuritypriv->dot11DefKey[keyindex].skey[0], keylength);
>>     115                  length = ((union recv_frame *)precvframe)->u.hdr.len-prxattrib->hdrlen-prxattrib->iv_len;
>>     116
>>     117                  payload = pframe+prxattrib->iv_len+prxattrib->hdrlen;
>>     118
>>     119                  /* decrypt payload include icv */
>>     120                  arc4_setkey(ctx, wepkey, 3 + keylength);
>>     121                  arc4_crypt(ctx, payload, payload,  length);
>>     122
>>     123                  /* calculate icv and compare the icv */
>>     124                  crc = cpu_to_le32(~crc32_le(~0, payload, length - 4));
>>     125
>>     126          }
>>     127  }
>>     128
>>
>> ---
>> 0-DAY CI Kernel Test Service, Intel Corporation
>> https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org
> This warning was introduced by my pull request,
> but I am fixing the sparse warning and the unused variable was
> declared in the previous commit.
> The original author did not compare the crc and payload in
> rtw_wep_decrypt, so the variable 'crc' was set but not used.
>
> Should I fix this in my pull request?
> BTW, in the following message, it mentioned *If you fix the issue,
> kindly add following tag as appropriate*,
> What's the meaning of the _tag_?

Hi jmhuang,

It means you can add 'Reported-by' tag in a fix commit, but
you can ignore it if you fix it in the original patch.

Best Regards,
Rong Chen

>
> thanks.
>
> --jmhuang
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