linux-kernel - [PATCH] staging: rtl8188eu: Replace a custom function with crc32

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Message-Id: <20210701133809.26534-1-fmdefrancesco@gmail.com>
Date:   Thu,  1 Jul 2021 15:38:09 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Larry Finger <Larry.Finger@...inger.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Cc:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Subject: [PATCH] staging: rtl8188eu: Replace a custom function with crc32_le()

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@...il.com>
---
 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);
 
 					arcfour_init(&mycontext, rc4key, 16);
 					arcfour_encrypt(&mycontext, payload, payload, length);
 					arcfour_encrypt(&mycontext, payload + length, crc, 4);
 				} else {
 					length = pxmitpriv->frag_len - pattrib->hdrlen - pattrib->iv_len - pattrib->icv_len;
-					*((__le32 *)crc) = getcrc32(payload, length);/* modified by Amy*/
+					*((__le32 *)crc) = ~crc32_le(~0, payload, length);
+
 					arcfour_init(&mycontext, rc4key, 16);
 					arcfour_encrypt(&mycontext, payload, payload, length);
 					arcfour_encrypt(&mycontext, payload + length, crc, 4);
@@ -682,7 +668,7 @@ u32 rtw_tkip_decrypt(struct adapter *padapter, struct recv_frame *precvframe)
 			arcfour_init(&mycontext, rc4key, 16);
 			arcfour_encrypt(&mycontext, payload, payload, length);
 
-			*((__le32 *)crc) = getcrc32(payload, length - 4);
+			*((__le32 *)crc) = ~crc32_le(~0, payload, length - 4);
 
 			if (crc[3] != payload[length - 1] ||
 			    crc[2] != payload[length - 2] ||
-- 
2.32.0