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From:   David Laight <David.Laight@ACULAB.COM>
To:     'Jhih-Ming Huang' <fbihjmeric@gmail.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "fabioaiuto83@gmail.com" <fabioaiuto83@gmail.com>,
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        "marcocesati@gmail.com" <marcocesati@gmail.com>,
        "linux-staging@lists.linux.dev" <linux-staging@lists.linux.dev>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v5] rtw_security: fix cast to restricted __le32
Thread-Topic: [PATCH v5] rtw_security: fix cast to restricted __le32
Thread-Index: AQHXZnYzS3EO6qxolE+NbuqnsEK0NKsfxZUw
Date:   Tue, 22 Jun 2021 09:31:54 +0000
Message-ID: <bdc0c31a7d28426995d229eb9014cd2b@AcuMS.aculab.com>
References: <20210619075255.107807-1-fbihjmeric@gmail.com>
 <20210621081928.145203-1-fbihjmeric@gmail.com>
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From: Jhih-Ming Huang
> Sent: 21 June 2021 09:19
> 
> 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.
...
> 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
...
> @@ -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)

Shouldn't this be using (IIRC) get_unaligned_le32() ?

	David

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