linux-kernel - Re: [PATCH v5] rtw_security: fix cast to restricted _

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Date:   Mon, 21 Jun 2021 23:51:04 +0800
From:   Jhih-Ming Huang <fbihjmeric@...il.com>
To:     gregkh@...uxfoundation.org, fabioaiuto83@...il.com,
        ross.schm.dev@...il.com, maqianga@...ontech.com,
        marcocesati@...il.com, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] rtw_security: fix cast to restricted __le32

On Mon, Jun 21, 2021 at 04:19:28PM +0800, Jhih-Ming Huang wrote:
> This patch fixes the sparse warning of fix cast to restricted __le32.
> 
> There was a change for replacing private CRC-32 routines with in kernel
> ones.
> However, the author used le32_to_cpu to convert crc32_le(), and we
> should cpu_to_le32.
> 
> Ths commit also fixes the payload checking by memcmp instead of checking element
> by element and removes the unused variable.
> 
> Signed-off-by: Jhih-Ming Huang <fbihjmeric@...il.com>

I forgot to add the Reported-by tag. 
already added in PATCH v6

thanks.

jmhuang

> ---
>  drivers/staging/rtl8723bs/core/rtw_security.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/staging/rtl8723bs/core/rtw_security.c b/drivers/staging/rtl8723bs/core/rtw_security.c
> index a99f439328f1..8dc6a976b487 100644
> --- a/drivers/staging/rtl8723bs/core/rtw_security.c
> +++ b/drivers/staging/rtl8723bs/core/rtw_security.c
> @@ -92,7 +92,6 @@ void rtw_wep_encrypt(struct adapter *padapter, u8 *pxmitframe)
>  void rtw_wep_decrypt(struct adapter  *padapter, u8 *precvframe)
>  {
>  	/*  exclude ICV */
> -	u8 crc[4];
>  	signed int	length;
>  	u32 keylength;
>  	u8 *pframe, *payload, *iv, wepkey[16];
> @@ -119,10 +118,6 @@ void rtw_wep_decrypt(struct adapter  *padapter, u8 *precvframe)
>  		/* decrypt payload include icv */
>  		arc4_setkey(ctx, wepkey, 3 + keylength);
>  		arc4_crypt(ctx, payload, payload,  length);
> -
> -		/* calculate icv and compare the icv */
> -		*((u32 *)crc) = le32_to_cpu(~crc32_le(~0, payload, length - 4));
> -
>  	}
>  }
>  
> @@ -537,7 +532,7 @@ u32 rtw_tkip_decrypt(struct adapter *padapter, u8 *precvframe)
>  	u32 pnh;
>  	u8   rc4key[16];
>  	u8   ttkey[16];
> -	u8 crc[4];
> +	__le32 crc;
>  	signed int			length;
>  
>  	u8 *pframe, *payload, *iv, *prwskey;
> @@ -618,10 +613,9 @@ u32 rtw_tkip_decrypt(struct adapter *padapter, u8 *precvframe)
>  			arc4_setkey(ctx, rc4key, 16);
>  			arc4_crypt(ctx, payload, payload, length);
>  
> -			*((u32 *)crc) = le32_to_cpu(~crc32_le(~0, payload, length - 4));
> +			crc = cpu_to_le32(~crc32_le(~0, payload, length - 4));
>  
> -			if (crc[3] != payload[length - 1] || crc[2] != payload[length - 2] ||
> -			    crc[1] != payload[length - 3] || crc[0] != payload[length - 4])
> +			if (memcmp(&crc, payload + length - 4, 4) != 0)
>  				res = _FAIL;
>  		} else {
>  			res = _FAIL;
> -- 
> 2.32.0
>