Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 10 Dec 2020 08:49:50 +1100
From:   Stephen Rothwell <sfr@canb.auug.org.au>
To:     Kees Cook <keescook@chromium.org>
Cc:     Dmitry Vyukov <dvyukov@google.com>, akpm@linux-foundation.org,
        andreyknvl@google.com, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Marco Elver <elver@google.com>
Subject: Re: [PATCH] kcov: don't instrument with UBSAN
Message-ID: <20201210084950.208c89ba@canb.auug.org.au>
In-Reply-To: <202012091054.08D70D4F@keescook>
References: <20201209100152.2492072-1-dvyukov@google.com>
        <202012091054.08D70D4F@keescook>
MIME-Version: 1.0
Content-Type: multipart/signed; boundary="Sig_/Bv6x0ikC3MH.6utRbkJsmF_";
 protocol="application/pgp-signature"; micalg=pgp-sha256
Precedence: bulk

--Sig_/Bv6x0ikC3MH.6utRbkJsmF_
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: quoted-printable

Hi all,

On Wed, 9 Dec 2020 10:54:39 -0800 Kees Cook <keescook@chromium.org> wrote:
>
> On Wed, Dec 09, 2020 at 11:01:52AM +0100, Dmitry Vyukov wrote:
> > Both KCOV and UBSAN use compiler instrumentation. If UBSAN detects a bug
> > in KCOV, it may cause infinite recursion via printk and other common
> > functions. We already don't instrument KCOV with KASAN/KCSAN for this
> > reason, don't instrument it with UBSAN as well.
> >=20
> > As a side effect this also resolves the following gcc warning:
> >=20
> > conflicting types for built-in function '__sanitizer_cov_trace_switch';
> > expected 'void(long unsigned int,  void *)' [-Wbuiltin-declaration-mism=
atch]
> >=20
> > It's only reported when kcov.c is compiled with any of the sanitizers
> > enabled. Size of the arguments is correct, it's just that gcc uses 'lon=
g'
> > on 64-bit arches and 'long long' on 32-bit arches, while kernel type is
> > always 'long long'.
> >=20
> > Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> > Suggested-by: Marco Elver <elver@google.com>
> > Signed-off-by: Dmitry Vyukov <dvyukov@google.com> =20
>=20
> Reviewed-by: Kees Cook <keescook@chromium.org>
>=20
> Thanks for chasing this down!
>=20
> Andrew, can you add this to the stack of ubsan patches you're carrying,
> please?

Added to linux-next today.

--=20
Cheers,
Stephen Rothwell

--Sig_/Bv6x0ikC3MH.6utRbkJsmF_
Content-Type: application/pgp-signature
Content-Description: OpenPGP digital signature

-----BEGIN PGP SIGNATURE-----

iQEzBAEBCAAdFiEENIC96giZ81tWdLgKAVBC80lX0GwFAl/RRn4ACgkQAVBC80lX
0Gx0rQf9FjZqWLlSg8chBznagG08qJuEV4mhrUiKjKEZuLw403VfIKXJwqcVNGiF
nR1lISGeRZTgCR9jP+0nWCPucghMIdHsOhWv678HvEiDLf+IL0er45ht/2rjH57g
ILDRwH60FyWnEAFk3gnmfsugWfFLJQhOYav2SFfGSOBkUEYDUVWFqdRhRW5fyvXn
kbVEUowz+QGZWqwTqY8tBj36GCOttjyqn4n3g0sRRMkV2NUdRIFKbfAQG1u9JIr+
N0H/hdH+G79cr9oo3u6msxvVWd/y2tfRv6VrdL9VQZ42oUc1MuZ+Ds/K4kua2tyW
3c+mdPIE2Cg7BbnBCvwIpDBWFlO9Fg==
=giMY
-----END PGP SIGNATURE-----

--Sig_/Bv6x0ikC3MH.6utRbkJsmF_--