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From:   Eric Dumazet <edumazet@google.com>
Date:   Wed, 18 Oct 2023 09:36:25 +0200
Message-ID: <CANn89iLSKJroojadGD2hvec8EyeUA5TPMKd=PmBzCJ7h2HF0zA@mail.gmail.com>
Subject: Re: [PATCH] amd64: Fix csum_partial_copy_generic()
To:     gus Gusenleitner Klaus <gus@keba.com>,
        Noah Goldstein <goldstein.w.n@gmail.com>
Cc:     lkml <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "bp@alien8.de" <bp@alien8.de>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "x86@kernel.org" <x86@kernel.org>, "hpa@zytor.com" <hpa@zytor.com>,
        "David S. Miller" <davem@davemloft.net>,
        "dsahern@kernel.org" <dsahern@kernel.org>,
        "kuba@kernel.org" <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
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On Wed, Oct 18, 2023 at 8:18=E2=80=AFAM gus Gusenleitner Klaus <gus@keba.co=
m> wrote:
>
> The checksum calculation is wrong in case of an source buffer
> containing zero bytes only. The expected return value is 0, the
> actual return value is 0xfffffff.
>
> This problem occurs when a ICMP echo reply is sent that has set
> zero identifier, sequence number and data.
>
> Signed-off-by: Klaus Gusenleitner <gus@keba.com>
> ---
>  arch/x86/lib/csum-copy_64.S | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/lib/csum-copy_64.S b/arch/x86/lib/csum-copy_64.S
> index d9e16a2cf285..c8391b4f3dea 100644
> --- a/arch/x86/lib/csum-copy_64.S
> +++ b/arch/x86/lib/csum-copy_64.S
> @@ -44,7 +44,7 @@ SYM_FUNC_START()
>         movq  %r13, 3*8(%rsp)
>         movq  %r15, 4*8(%rsp)
>
> -       movl  $-1, %eax
> +       movl  $0, %eax
>         xorl  %r9d, %r9d
>         movl  %edx, %ecx
>         cmpl  $8, %ecx
> --
> 2.30.2
>

Lets CC Noah Goldstein <goldstein.w.n@gmail.com> (I thought Noah wrote
some kunit tests, maybe I am wrong)

When was this bug added ?

A Fixes: tag is very much needed, and would be a needed step to CC the
original author.

Thanks.