MIPS: Fix special case in 64 bit IP checksumming.

commit 66fd848cad upstream.

For certain arguments such as saddr = 0xc0a8fd60, daddr = 0xc0a8fda1,
len = 80, proto = 17, sum = 0x7eae049d there will be a carry when
folding the intermediate 64 bit checksum to 32 bit but the code doesn't
add the carry back to the one's complement sum, thus an incorrect result
will be generated.

Reported-by: Mark Zhang <bomb.zhang@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ralf Baechle
2017-01-26 02:16:47 +01:00
committed by Greg Kroah-Hartman
parent a8af2054e9
commit ef674c5eb8

View File

@ -186,7 +186,9 @@ static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
" daddu %0, %4 \n"
" dsll32 $1, %0, 0 \n"
" daddu %0, $1 \n"
" sltu $1, %0, $1 \n"
" dsra32 %0, %0, 0 \n"
" addu %0, $1 \n"
#endif
" .set pop"
: "=r" (sum)