From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754435Ab3C0UGW (ORCPT ); Wed, 27 Mar 2013 16:06:22 -0400 Received: from webmail.solarflare.com ([12.187.104.25]:47823 "EHLO webmail.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754192Ab3C0UGU (ORCPT ); Wed, 27 Mar 2013 16:06:20 -0400 Message-ID: <1364414776.2922.19.camel@bwh-desktop.uk.solarflarecom.com> Subject: Re: [PATCH -next] GRE: Use strlcat() for size checking From: Ben Hutchings To: Geert Uytterhoeven CC: Pravin B Shelar , "David S. Miller" , , , Date: Wed, 27 Mar 2013 20:06:16 +0000 In-Reply-To: <1364410111-29418-1-git-send-email-geert@linux-m68k.org> References: <1364410111-29418-1-git-send-email-geert@linux-m68k.org> Organization: Solarflare Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 (3.2.3-3.fc16) Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-Originating-IP: [10.17.20.137] X-TM-AS-Product-Ver: SMEX-10.0.0.1412-7.000.1014-19750.005 X-TM-AS-Result: No--14.054000-0.000000-31 X-TM-AS-User-Approved-Sender: Yes X-TM-AS-User-Blocked-Sender: No Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2013-03-27 at 19:48 +0100, Geert Uytterhoeven wrote: > On m68k, gcc tries to be smart and turns > > strncat(name, "%d", 2); > > into a call to strlen() and a 16-bit store, causing a link failure, > as arch/m68k/include/asm/string.h provides strlen() using a macro: > > ERROR: "strlen" [net/ipv4/ip_tunnel.ko] undefined! Perhaps you should fix the string library for m68k, then! > Use strlcat() instead to avoid this, which also allows to simplify the > check for buffer overflows. It looks like you're also fixing an off-by-one error: the maximum length of ops->kind will be IFNAMSIZ - 3 (just enough to add "%d" and the null terminator), rather than IFNAMSIZ - 4. Ben. > Signed-off-by: Geert Uytterhoeven > -- > Compile-tested only > > http://kisskb.ellerman.id.au/kisskb/buildresult/8462108/ > --- > net/ipv4/ip_tunnel.c | 5 ++--- > 1 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c > index 9d96b68..8dbe672 100644 > --- a/net/ipv4/ip_tunnel.c > +++ b/net/ipv4/ip_tunnel.c > @@ -284,12 +284,11 @@ static struct net_device *__ip_tunnel_create(struct net *net, > if (parms->name[0]) > strlcpy(name, parms->name, IFNAMSIZ); > else { > - if (strlen(ops->kind) + 3 >= IFNAMSIZ) { > + strlcpy(name, ops->kind, IFNAMSIZ); > + if (strlcat(name, "%d", IFNAMSIZ) >= IFNAMSIZ) { > err = -E2BIG; > goto failed; > } > - strlcpy(name, ops->kind, IFNAMSIZ); > - strncat(name, "%d", 2); > } > > ASSERT_RTNL(); -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.