From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id CAC923858C83; Wed, 12 Apr 2023 08:46:19 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org CAC923858C83
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1681289179;
	bh=u/UYc/gXm7A/sJuyHm096zC+reILY46k991lm616ixY=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=blBGSNMl30DXAv932wro3Rwc1qqKFR6xY+CwBcBX9X9sWQ9rNNaUhGozPgvVL7R1s
	 gzlIeZhEAHNAp0GLTMtADGp0kg6uaiCLM4Rkz6z3nc7GlswfPxLWe1uDcr830NBX9z
	 resEPqnfgDIA4cK4LFGy2nqfQJ14JMq5Vrf3sB1Y=
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug sanitizer/109446] Possible destination array overflow without
 diagnosis in memcpy
Date: Wed, 12 Apr 2023 08:46:18 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: sanitizer
X-Bugzilla-Version: 8.4.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-109446-4-6bhI13QkNj@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109446-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109446-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109446

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Martin Li=C5=A1ka from comment #5)
> > It seems Clang disables this optimization and convert memcpy to
> > __asan_memcpy calls if -fsanitize=3Daddress used:
> >=20
> > https://godbolt.org/z/dcfadoMYY
>=20
> Yep! Richi, do you know a place where we lower this?

gimple_fold_builtin_memory_op

not sure if we should prevent all of those transforms.  But the question is
why ASAN doesn't instrument the generated aggregate copy?  Maybe because
in C/C++ you cannot write an aggregate array copy?=