On Mon, Jun 14, 2021 at 11:27:03PM +0800, Jhih Ming Huang wrote: > Thanks for your explanation. > > To clarify, even though it might be false positives in some senses, > following "hold the variable native-endian and check the conversion > done correctly" > is much easier than the other way. And it's exactly the current implementation. > > So it's better to keep the current implementation and ignore the > warnings, right? Umm... If that's the case, the warnings should go away if you use cpu_to_le32() for conversions from native to l-e and le32_to_cpu() for conversions from l-e to native. IOW, the choice between those should annotate what's going on. In your case doing *((u32 *)crc) = le32_to_cpu((__force __le32)~crc32_le(~0, payload, length - 4)); is wrong - you have crc32_le(...) native-endian ~crc32_le(...) - ditto le32_to_cpu(~crc32_le(...)) - byteswapped native-endian on b-e, unchanged on l-e. So result will be little-endian representation of ~crc32(...) in all cases. IOW, it's cpu_to_le32(~crc32_le(...)), misannotated as native-endian instead of little-endian it actually is. Then you store that value (actually __le32) into *(u32 *)crc. Seeing that crc is u8[4] there, that *(u32 *) is misleading - you are actually storing __le32 there (and, AFAICS, doing noting with the result). The same story in rtw_tkip_decrypt(), only there you do use the result later. So just make it __le32 crc and crc = cpu_to_le32(~crc32_le(~0, payload, length - 4)); with if (crc[3] != payload[length - 1] || crc[2] != payload[length - 2] || crc[1] != payload[length - 3] || crc[0] != payload[length - 4]) turned into if (memcmp(&crc, payload + length - 4, 4) != 0) (or (crc != get_unaligned((__le32 *)(payload + length - 4))), for that matter, to document what's going on and let the damn thing pick the optimal implementation for given architecture). Incidentally, your secmicgetuint32() is simply get_unaligned_le32() and secmicputuint32() - put_unaligned_le32(). No need to reinvent that wheel...
