From: Charlie Jenkins <charlie@rivosinc.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Helge Deller <deller@gmx.de>,
"James E . J . Bottomley" <James.Bottomley@hansenpartnership.com>,
linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org,
Palmer Dabbelt <palmer@rivosinc.com>
Subject: Re: [PATCH] parisc: Fix csum_ipv6_magic on 32-bit systems
Date: Tue, 13 Feb 2024 20:15:19 -0500 [thread overview]
Message-ID: <ZcwUJzD9eGF+AIP0@ghost> (raw)
In-Reply-To: <20240210191556.3761064-1-linux@roeck-us.net>
On Sat, Feb 10, 2024 at 11:15:56AM -0800, Guenter Roeck wrote:
> 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: Charlie Jenkins <charlie@rivosinc.com>
> Cc: Palmer Dabbelt <palmer@rivosinc.com>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
> 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 f705e5dd1074..e619e67440db 100644
> --- a/arch/parisc/include/asm/checksum.h
> +++ b/arch/parisc/include/asm/checksum.h
> @@ -163,7 +163,8 @@ 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),
> --
> 2.39.2
>
Looks good!
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
prev parent reply other threads:[~2024-02-14 1:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-10 19:15 [PATCH] parisc: Fix csum_ipv6_magic on 32-bit systems Guenter Roeck
2024-02-11 13:57 ` David Laight
2024-02-11 14:09 ` Guenter Roeck
2024-02-14 1:15 ` Charlie Jenkins [this message]
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