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From:   Francis Laniel <flaniel@linux.microsoft.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-kernel@vger.kernel.org,
        Alban Crequy <alban.crequy@gmail.com>,
        Alban Crequy <albancrequy@microsoft.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        Mykola Lysenko <mykolal@fb.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        Shuah Khan <shuah@kernel.org>, linux-mm@kvack.org,
        bpf@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [RFC PATCH v1 1/2] maccess: fix writing offset in case of fault in strncpy_from_kernel_nofault()
Date:   Wed, 09 Nov 2022 12:04:24 +0100
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In-Reply-To: <20221108130551.85ad67b402582e3855418294@linux-foundation.org>
References: <20221108195211.214025-1-flaniel@linux.microsoft.com> <20221108195211.214025-2-flaniel@linux.microsoft.com> <20221108130551.85ad67b402582e3855418294@linux-foundation.org>
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Hi.

Le mardi 8 novembre 2022, 22:05:51 CET Andrew Morton a =E9crit :
> On Tue,  8 Nov 2022 20:52:06 +0100 Francis Laniel=20
<flaniel@linux.microsoft.com> wrote:
> > From: Alban Crequy <albancrequy@microsoft.com>
> >=20
> > If a page fault occurs while copying the first byte, this function rese=
ts
> > one byte before dst.
> > As a consequence, an address could be modified and leaded to kernel
> > crashes if case the modified address was accessed later.
> >=20
> > Signed-off-by: Alban Crequy <albancrequy@microsoft.com>
> > Tested-by: Francis Laniel <flaniel@linux.microsoft.com>
>=20
> Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
>=20
> Please merge via the bpf tree.
>=20
> This looks potentially nasty.  Fortunately only tracing code uses it,
> but I'm thinking it should have cc:stable and a Fixes:?

Thank you for the review!
Sorry, I thought to add stable list but forgot to add it when sending the=20
series...
I will sent a v2 with your review and without rfc tag to, among others,=20
stable.