linux-kernel - [fbihjmeric@...il.com: Re: drivers/staging/rtl8723bs/core/rtw_security.c:95:9: warning: variable 'crc' set but not used]

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Message-ID: <20210621063041.v4u35pxgglgwn2go@gmail.com>
Date:   Mon, 21 Jun 2021 14:30:41 +0800
From:   Jhih-Ming Huang <fbihjmeric@...il.com>
To:     linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [fbihjmeric@...il.com: Re:
 drivers/staging/rtl8723bs/core/rtw_security.c:95:9: warning: variable 'crc'
 set but not used]

On Sat, Jun 19, 2021 at 6:27 PM kernel test robot <lkp@...el.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@...el.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@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?

thanks.

--jmhuang