5.4-stable review patch. If anyone has any objections, please let me know.
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From: Guenter Roeck linux@roeck-us.net
[ Upstream commit 4408ba75e4ba80c91fde7e10bccccf388f5c09be ]
Calculating the IPv6 checksum on 32-bit systems missed overflows when adding the proto+len fields into the checksum. This results in the following unit test failure.
# test_csum_ipv6_magic: ASSERTION FAILED at lib/checksum_kunit.c:506 Expected ( u64)csum_result == ( u64)expected, but ( u64)csum_result == 46722 (0xb682) ( u64)expected == 46721 (0xb681) not ok 5 test_csum_ipv6_magic
This is probably rarely seen in the real world because proto+len are usually small values which will rarely result in overflows when calculating the checksum. However, the unit test code uses large values for the length field, causing the test to fail.
Fix the problem by adding the missing carry into the final checksum.
Cc: Palmer Dabbelt palmer@rivosinc.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Guenter Roeck linux@roeck-us.net Tested-by: Charlie Jenkins charlie@rivosinc.com Reviewed-by: Charlie Jenkins charlie@rivosinc.com Signed-off-by: Helge Deller deller@gmx.de Signed-off-by: Sasha Levin sashal@kernel.org --- arch/parisc/include/asm/checksum.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/parisc/include/asm/checksum.h b/arch/parisc/include/asm/checksum.h index 7efcd901b9656..0a02639514505 100644 --- a/arch/parisc/include/asm/checksum.h +++ b/arch/parisc/include/asm/checksum.h @@ -178,7 +178,8 @@ static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr, " ldw,ma 4(%2), %7\n" /* 4th daddr */ " addc %6, %0, %0\n" " addc %7, %0, %0\n" -" addc %3, %0, %0\n" /* fold in proto+len, catch carry */ +" addc %3, %0, %0\n" /* fold in proto+len */ +" addc 0, %0, %0\n" /* add carry */
#endif : "=r" (sum), "=r" (saddr), "=r" (daddr), "=r" (len),