From 64a857fe8928e4d3003711676bd1c516257ab6c4 Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Tue, 13 Feb 2024 15:46:31 -0800 Subject: [PATCH] parisc: Fix csum_ipv6_magic on 64-bit systems [ Upstream commit 4b75b12d70506e31fc02356bbca60f8d5ca012d0 ] hppa 64-bit systems calculates the IPv6 checksum using 64-bit add operations. The last add folds protocol and length fields into the 64-bit result. While unlikely, this operation can overflow. The overflow can be triggered with a code sequence such as the following. /* try to trigger massive overflows */ memset(tmp_buf, 0xff, sizeof(struct in6_addr)); csum_result = csum_ipv6_magic((struct in6_addr *)tmp_buf, (struct in6_addr *)tmp_buf, 0xffff, 0xff, 0xffffffff); Fix the problem by adding any overflows from the final add operation into the calculated checksum. Fortunately, we can do this without additional cost by replacing the add operation used to fold the checksum into 32 bit with "add,dc" to add in the missing carry. Cc: Palmer Dabbelt Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Guenter Roeck Reviewed-by: Charlie Jenkins Tested-by: Guenter Roeck Signed-off-by: Helge Deller Signed-off-by: Sasha Levin --- arch/parisc/include/asm/checksum.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/parisc/include/asm/checksum.h b/arch/parisc/include/asm/checksum.h index e619e67440db..c949aa20fa16 100644 --- a/arch/parisc/include/asm/checksum.h +++ b/arch/parisc/include/asm/checksum.h @@ -137,8 +137,8 @@ static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr, " add,dc %3, %0, %0\n" /* fold in proto+len | carry bit */ " extrd,u %0, 31, 32, %4\n"/* copy upper half down */ " depdi 0, 31, 32, %0\n"/* clear upper half */ -" add %4, %0, %0\n" /* fold into 32-bits */ -" addc 0, %0, %0\n" /* add carry */ +" add,dc %4, %0, %0\n" /* fold into 32-bits, plus carry */ +" addc 0, %0, %0\n" /* add final carry */ #else