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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47A59EB64D9 for ; Mon, 10 Jul 2023 13:13:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230119AbjGJNNP convert rfc822-to-8bit (ORCPT ); Mon, 10 Jul 2023 09:13:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229736AbjGJNNM (ORCPT ); Mon, 10 Jul 2023 09:13:12 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7500EBB for ; Mon, 10 Jul 2023 06:13:10 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-286-g_5tey9eP9ugS51RLSz6Gw-1; Mon, 10 Jul 2023 14:13:07 +0100 X-MC-Unique: g_5tey9eP9ugS51RLSz6Gw-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Mon, 10 Jul 2023 14:13:06 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Mon, 10 Jul 2023 14:13:06 +0100 From: David Laight To: 'Azeem Shaikh' , Greg Kroah-Hartman CC: "linux-hardening@vger.kernel.org" , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] kobject: Replace strlcpy with strscpy Thread-Topic: [PATCH] kobject: Replace strlcpy with strscpy Thread-Index: AQHZrdj8Qo2zsxXODk+YaMEZxqXK9K+zA4Wg Date: Mon, 10 Jul 2023 13:13:06 +0000 Message-ID: References: <20230703180528.3709258-1-azeemshaikh38@gmail.com> In-Reply-To: <20230703180528.3709258-1-azeemshaikh38@gmail.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Azeem Shaikh > Sent: 03 July 2023 19:05 > > strlcpy() reads the entire source buffer first. > This read may exceed the destination size limit. > This is both inefficient and can lead to linear read > overflows if a source string is not NUL-terminated [1]. > In an effort to remove strlcpy() completely [2], replace > strlcpy() here with strscpy(). > > Direct replacement is safe here since return value of -errno > is used to check for truncation instead of sizeof(dest). > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy > [2] https://github.com/KSPP/linux/issues/89 > > Signed-off-by: Azeem Shaikh > --- > lib/kobject_uevent.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c > index 7c44b7ae4c5c..e5497fa0a2d2 100644 > --- a/lib/kobject_uevent.c > +++ b/lib/kobject_uevent.c > @@ -254,8 +254,8 @@ static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem) > int buffer_size = sizeof(env->buf) - env->buflen; > int len; > > - len = strlcpy(&env->buf[env->buflen], subsystem, buffer_size); > - if (len >= buffer_size) { > + len = strscpy(&env->buf[env->buflen], subsystem, buffer_size); > + if (len < 0) { > pr_warn("init_uevent_argv: buffer size of %d too small, needed %d\n", > buffer_size, len); > return -ENOMEM; The size in the error message is now wrong. It has to be said that mostly all the strings that get copied in the kernel are '\0' terminated - so maybe it is all moot. OTOH printing (at least some of) the string that didn't fit is a lot more useful than its length. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)