Hi David,

This driver is going to be replaced by a "better" version, so I'm not sure 
whether or not this patch is still needed.

However, I see that we have similar problems in rtl8723bs and perhaps also in 
other drivers. Therefore, I'd like to solve this problem, whatever will happen 
to the "worse" rti8188eu, and change the code where else it needs to be 
changed.

Now I have a few questions... 

On Thursday, July 22, 2021 5:30:08 PM CEST David Laight wrote:

From: Fabio M. De Francesco

quoted

Sent: 21 July 2021 12:01

Use crc32_le() in place of the custom getcrc32().

...

quoted

@@ -609,14 +595,15 @@ u32	rtw_tkip_encrypt(struct adapter *padapter, 

struct xmit_frame

quoted

*pxmitframe)

 				if ((curfragnum + 1) == pattrib-

nr_frags) {	/* 4 the last fragment */

quoted

 				
 					length = pattrib-

last_txcmdsz - pattrib->hdrlen - pattrib->iv_len -

quoted

pattrib->icv_len;
-					*((__le32 *)crc) = 

getcrc32(payload, length);/* modified by Amy*/

quoted

+					*((__le32 *)crc) = 

cpu_to_le32(~crc32_le(~0, payload, length));

quoted

arcfour_init(&mycontext, rc4key, 16);

quoted

arcfour_encrypt(&mycontext, payload, payload, length);

quoted

arcfour_encrypt(&mycontext, payload + length, crc, 4);

quoted

 				
 				} else {
 				
 					length = pxmitpriv-

frag_len - pattrib->hdrlen - pattrib->iv_len -

quoted

pattrib->icv_len;
-					*((__le32 *)crc) = 

getcrc32(payload, length);/* modified by Amy*/

quoted

+					*((__le32 *)crc) = 

cpu_to_le32(~crc32_le(~0, payload, length));

quoted

+

 					

arcfour_init(&mycontext, rc4key, 16);

quoted

arcfour_encrypt(&mycontext, payload, payload, length);

quoted

arcfour_encrypt(&mycontext, payload + length, crc, 4);

Change crc to be __le32, kill the casts and pass &crc in the last call.

I could do it, but the last call (that to arcfour_encrypt() takes a pointer to 
u8 type as the third parameter. How can I use a __le32 for that?

I think that one possible solution is to change crc to be an union and use two 
fields in the following lines:

union {
	__le32 f0; /* More descriptive name? */
	u8 f1[4]; /* More descriptive name? */
} crc;

[...]

crc.f0 = cpu_to_le32(~crc32_le(~0, payload, length - 4));

[...]

arcfour_encrypt(&mycontext, payload + length, crc.f1, 4);

Please, tell me... What about the solution above?

quoted

@@ -682,7 +669,7 @@ u32 rtw_tkip_decrypt(struct adapter *padapter, struct 

recv_frame

quoted

*precvframe)> 
 			arcfour_init(&mycontext, rc4key, 16);
 			arcfour_encrypt(&mycontext, payload, 

payload, length);

quoted

-			*((__le32 *)crc) = getcrc32(payload, length 

- 4);

quoted

+			*((__le32 *)crc) = cpu_to_le32(~crc32_le(~0, 

payload, length - 4));

quoted

 			if (crc[3] != payload[length - 1] ||
 			
 			    crc[2] != payload[length - 2] ||

You could to the same here, or make crc u32, remove the cpu_to_le32()
and use get_unaligned_u32(payload + length - 4) (or whatever it is called).

Sorry, I can't understand this line. Can you please elaborate it a bit more?

But it is much better to do:
	crc = crc32_le(~0, payload, length);
	if (crc != VALID_CRC32)
		res = _FAIL;

Why "crc = crc32_le(~0, payload, length);"? Shouldn't it be "crc = 
cpu_to_le32(~crc32_le(~0, patload, length);"? 

Why did you drop both the cpu_to_le32() call and the '~' operator?

Thanks in advance,

Fabio

You can lookup VALID_CRC32, but it is crc32_le(0, "\xff\xff\xff\xff", 4);

	David

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