From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20730C433E3 for ; Tue, 18 Aug 2020 09:51:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0BBDD206B5 for ; Tue, 18 Aug 2020 09:51:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726684AbgHRJv3 (ORCPT ); Tue, 18 Aug 2020 05:51:29 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:48908 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726353AbgHRJv2 (ORCPT ); Tue, 18 Aug 2020 05:51:28 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 0EEFE1C0BB7; Tue, 18 Aug 2020 11:51:25 +0200 (CEST) Date: Tue, 18 Aug 2020 11:51:24 +0200 From: Pavel Machek To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, jbaron@akamai.com, Jim Cromie , Sasha Levin Subject: Re: [PATCH 4.19 051/168] dyndbg: fix a BUG_ON in ddebug_describe_flags Message-ID: <20200818095124.GD10974@amd> References: <20200817143733.692105228@linuxfoundation.org> <20200817143736.291298404@linuxfoundation.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="UfEAyuTBtIjiZzX6" Content-Disposition: inline In-Reply-To: <20200817143736.291298404@linuxfoundation.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --UfEAyuTBtIjiZzX6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon 2020-08-17 17:16:22, Greg Kroah-Hartman wrote: > From: Jim Cromie >=20 > [ Upstream commit f678ce8cc3cb2ad29df75d8824c74f36398ba871 ] >=20 > ddebug_describe_flags() currently fills a caller provided string buffer, > after testing its size (also passed) in a BUG_ON. Fix this by > replacing them with a known-big-enough string buffer wrapped in a > struct, and passing that instead. >=20 > Also simplify ddebug_describe_flags() flags parameter from a struct to > a member in that struct, and hoist the member deref up to the caller. > This makes the function reusable (soon) where flags are unpacked. Original code was correct, passing explicit size, this passes strange structure. BUG_ON can never trigger in the origianl code, so this is not a bugfix. Best regards, Pavel > +++ b/lib/dynamic_debug.c > @@ -85,22 +85,22 @@ static struct { unsigned flag:8; char opt_char; } opt= _array[] =3D { > { _DPRINTK_FLAGS_NONE, '_' }, > }; > =20 > +struct flagsbuf { char buf[ARRAY_SIZE(opt_array)+1]; }; > + > /* format a string into buf[] which describes the _ddebug's flags */ > -static char *ddebug_describe_flags(struct _ddebug *dp, char *buf, > - size_t maxlen) > +static char *ddebug_describe_flags(unsigned int flags, struct flagsbuf *= fb) > { > - char *p =3D buf; > + char *p =3D fb->buf; > int i; > =20 > - BUG_ON(maxlen < 6); > for (i =3D 0; i < ARRAY_SIZE(opt_array); ++i) > - if (dp->flags & opt_array[i].flag) > + if (flags & opt_array[i].flag) > *p++ =3D opt_array[i].opt_char; > - if (p =3D=3D buf) > + if (p =3D=3D fb->buf) > *p++ =3D '_'; > *p =3D '\0'; > =20 > - return buf; > + return fb->buf; > } > =20 > #define vpr_info(fmt, ...) \ > @@ -142,7 +142,7 @@ static int ddebug_change(const struct ddebug_query *q= uery, > struct ddebug_table *dt; > unsigned int newflags; > unsigned int nfound =3D 0; > - char flagbuf[10]; > + struct flagsbuf fbuf; > =20 > /* search for matching ddebugs */ > mutex_lock(&ddebug_lock); > @@ -199,8 +199,7 @@ static int ddebug_change(const struct ddebug_query *q= uery, > vpr_info("changed %s:%d [%s]%s =3D%s\n", > trim_prefix(dp->filename), dp->lineno, > dt->mod_name, dp->function, > - ddebug_describe_flags(dp, flagbuf, > - sizeof(flagbuf))); > + ddebug_describe_flags(dp->flags, &fbuf)); > } > } > mutex_unlock(&ddebug_lock); > @@ -779,7 +778,7 @@ static int ddebug_proc_show(struct seq_file *m, void = *p) > { > struct ddebug_iter *iter =3D m->private; > struct _ddebug *dp =3D p; > - char flagsbuf[10]; > + struct flagsbuf flags; > =20 > vpr_info("called m=3D%p p=3D%p\n", m, p); > =20 > @@ -792,7 +791,7 @@ static int ddebug_proc_show(struct seq_file *m, void = *p) > seq_printf(m, "%s:%u [%s]%s =3D%s \"", > trim_prefix(dp->filename), dp->lineno, > iter->table->mod_name, dp->function, > - ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf))); > + ddebug_describe_flags(dp->flags, &flags)); > seq_escape(m, dp->format, "\t\r\n\""); > seq_puts(m, "\"\n"); > =20 --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --UfEAyuTBtIjiZzX6 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAl87pJwACgkQMOfwapXb+vK8egCeOuLFXFZ8DrogqMjVa0su9IUM VC8AoJu7I0GDnLFTdQOaAoQVu+f6tfKS =XkW2 -----END PGP SIGNATURE----- --UfEAyuTBtIjiZzX6--