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Tue, 31 Mar 2020 09:00:23 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-69.ams2.redhat.com [10.36.112.69]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9FA6F100EBB6; Tue, 31 Mar 2020 09:00:13 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 2778511385E2; Tue, 31 Mar 2020 11:00:12 +0200 (CEST) From: Markus Armbruster To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH 1/6] scripts/coccinelle: add error-use-after-free.cocci References: <20200324153630.11882-1-vsementsov@virtuozzo.com> <20200324153630.11882-2-vsementsov@virtuozzo.com> Date: Tue, 31 Mar 2020 11:00:12 +0200 In-Reply-To: <20200324153630.11882-2-vsementsov@virtuozzo.com> (Vladimir Sementsov-Ogievskiy's message of "Tue, 24 Mar 2020 18:36:25 +0300") Message-ID: <87bloc3nmr.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, zhang.zhanghailiang@huawei.com, qemu-block@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, qemu-devel@nongnu.org, marcandre.lureau@redhat.com, den@openvz.org, mreitz@redhat.com, jsnow@redhat.com, mdroth@linux.vnet.ibm.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Vladimir Sementsov-Ogievskiy writes: > Add script to find and fix trivial use-after-free of Error objects. > How to use: > spatch --sp-file scripts/coccinelle/auto-propagated-errp.cocci \ > --macro-file scripts/cocci-macro-file.h --in-place \ > --no-show-diff ( FILES... | --use-gitgrep . ) Pasto: you mean scripts/coccinelle/error-use-after-free.cocci. --use-gitgrep is just one of several methods. Any particular reason for recommending it over the others? > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > scripts/coccinelle/error-use-after-free.cocci | 52 +++++++++++++++++++ > MAINTAINERS | 1 + > 2 files changed, 53 insertions(+) > create mode 100644 scripts/coccinelle/error-use-after-free.cocci > > diff --git a/scripts/coccinelle/error-use-after-free.cocci b/scripts/cocc= inelle/error-use-after-free.cocci > new file mode 100644 > index 0000000000..7cfa42355b > --- /dev/null > +++ b/scripts/coccinelle/error-use-after-free.cocci > @@ -0,0 +1,52 @@ > +// Find and fix trivial use-after-free of Error objects > +// > +// Copyright (c) 2020 Virtuozzo International GmbH. > +// > +// This program is free software; you can redistribute it and/or > +// modify it under the terms of the GNU General Public License as > +// published by the Free Software Foundation; either version 2 of the > +// License, or (at your option) any later version. > +// > +// This program is distributed in the hope that it will be useful, > +// but WITHOUT ANY WARRANTY; without even the implied warranty of > +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > +// GNU General Public License for more details. > +// > +// You should have received a copy of the GNU General Public License > +// along with this program. If not, see > +// . > +// > +// How to use: > +// spatch --sp-file scripts/coccinelle/auto-propagated-errp.cocci \ > +// --macro-file scripts/cocci-macro-file.h --in-place \ > +// --no-show-diff ( FILES... | --use-gitgrep . ) Same pasto. I doubt including basic spatch instructions with every script is a good idea. Better explain it in one place, with proper maintenance. scripts/coccinelle/README? We could be a bit more verbose there, e.g. to clarify required vs. suggested options. > + > +@ exists@ > +identifier fn, fn2; > +expression err; > +@@ > + > + fn(...) > + { > + <... > +( > + error_free(err); > ++ err =3D NULL; > +| > + error_report_err(err); > ++ err =3D NULL; > +| > + error_reportf_err(err, ...); > ++ err =3D NULL; > +| > + warn_report_err(err); > ++ err =3D NULL; > +| > + warn_reportf_err(err, ...); > ++ err =3D NULL; > +) > + ... when !=3D err =3D NULL > + when !=3D exit(...) > + fn2(..., err, ...) > + ...> > + } This inserts err =3D NULL after error_free() if there is a path to a certain kind of use of @err without such an assignment. The "when !=3D exit()" part excludes certain "phony" paths. It's not a tight check; there are other ways to unconditionally terminate the process or jump elsewhere behind Coccinelle's back. Not a problem, the script is meant to have its output reviewed manually. Should we mention the need to review the script's output? > diff --git a/MAINTAINERS b/MAINTAINERS > index b5c86ec494..ba97cc43fc 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -2037,6 +2037,7 @@ F: include/qemu/error-report.h > F: qapi/error.json > F: util/error.c > F: util/qemu-error.c > +F: scripts/coccinelle/*err*.cocci Silently captures existing scripts in addition to this new one. Tolerable. The globbing looks rather brittle, though. > =20 > GDB stub > M: Alex Benn=C3=A9e