MIPS: Fix special case in 64 bit IP checksumming.

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 <[email protected]> Signed-off-by: Ralf Baechle <[email protected]> Reviewed-by: James Hogan <[email protected]> Cc: [email protected] Signed-off-by: James Hogan <[email protected]>
Axel1400 · Feb 17, 2017 · 66fd848 · 66fd848
1 parent 4da3273
commit 66fd848
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/arch/mips/include/asm/checksum.h b/arch/mips/include/asm/checksum.h
@@ -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)