RE: [PATCH 2/2] staging: rtl8723bs: fix cast to restricted __le32

David Laight
2021-08-19T09:43:47Z

From: Aakash Hemadri
> Sent: 16 August 2021 18:35
>
> Fix sparse warning:
> warning: cast to restricted __le32

How many different copies of this crappy copy are there?
>
...
> diff --git a/drivers/staging/rtl8723bs/core/rtw_security.c
> b/drivers/staging/rtl8723bs/core/rtw_security.c
> index 381deeea99d0..5320b1a46dfb 100644
> --- a/drivers/staging/rtl8723bs/core/rtw_security.c
> +++ b/drivers/staging/rtl8723bs/core/rtw_security.c
> @@ -122,7 +122,7 @@ void rtw_wep_decrypt(struct adapter *padapter, u8 *precvframe)
> arc4_crypt(ctx, payload, payload, length);
>
> /* calculate icv and compare the icv */
> - *((u32 *)crc) = le32_to_cpu(~crc32_le(~0, payload, length - 4));
> + *((u32 *)crc) = ~crc32_le(~0, payload, length - 4);

You've removed a byteswap which is needed on BE architectures.

> }
> }
> @@ -621,7 +621,7 @@ 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));
> + *((u32 *)crc) = ~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])

As above - crc32_le() does a 'little-endian crc' but returns a host-ordered value.
The (horrid) array cast means you need to store a LE value.

There are a dozen better ways to do this - I'm bored of quoting them.

David

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