Re: [PATCH] staging: rtl8188eu: Replace a custom function with crc32_le()

From: Greg Kroah-Hartman
Date: Tue Jul 13 2021 - 08:50:53 EST


On Thu, Jul 01, 2021 at 03:38:09PM +0200, Fabio M. De Francesco wrote:
> Use crc32_le in place of the custom getcrc32. This change makes GCC
> to warn about incorrect castings to the restricted type __le32, but
> they can be safely ignored because crc32_le calculates bitwise
> little-endian Ethernet AUTODIN II CRC32.
>
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx>
> ---
> drivers/staging/rtl8188eu/core/rtw_security.c | 22 ++++---------------
> 1 file changed, 4 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/staging/rtl8188eu/core/rtw_security.c b/drivers/staging/rtl8188eu/core/rtw_security.c
> index 1b2cb6196463..5f010cb66970 100644
> --- a/drivers/staging/rtl8188eu/core/rtw_security.c
> +++ b/drivers/staging/rtl8188eu/core/rtw_security.c
> @@ -111,21 +111,6 @@ static void crc32_init(void)
> bcrc32initialized = 1;
> }
>
> -static __le32 getcrc32(u8 *buf, int len)
> -{
> - u8 *p;
> - u32 crc;
> -
> - if (bcrc32initialized == 0)
> - crc32_init();
> -
> - crc = 0xffffffff; /* preload shift register, per CRC-32 spec */
> -
> - for (p = buf; len > 0; ++p, --len)
> - crc = crc32_table[(crc ^ *p) & 0xff] ^ (crc >> 8);
> - return cpu_to_le32(~crc); /* transmit complement, per CRC-32 spec */
> -}
> -
> /* Need to consider the fragment situation */
> void rtw_wep_encrypt(struct adapter *padapter, struct xmit_frame *pxmitframe)
> {
> @@ -609,14 +594,15 @@ u32 rtw_tkip_encrypt(struct adapter *padapter, struct xmit_frame *pxmitframe)
>
> if ((curfragnum + 1) == pattrib->nr_frags) { /* 4 the last fragment */
> length = pattrib->last_txcmdsz - pattrib->hdrlen - pattrib->iv_len - pattrib->icv_len;
> - *((__le32 *)crc) = getcrc32(payload, length);/* modified by Amy*/
> + *((__le32 *)crc) = ~crc32_le(~0, payload, length);

Why are you casting a native endian return value to a little endian
pointer? Are you _SURE_ that is correct?

We can not just ignore warnings, they are there for a reason. Or if
not, then fix the code up to not have the warnings, but I can't take
this as-is, sorry.

thanks,

greg k-h