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=-8.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_NEOMUTT autolearn=ham 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 0B6A4C65BAE for ; Thu, 13 Dec 2018 12:31:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD03620645 for ; Thu, 13 Dec 2018 12:31:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CD03620645 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729037AbeLMMbm (ORCPT ); Thu, 13 Dec 2018 07:31:42 -0500 Received: from mx2.suse.de ([195.135.220.15]:56694 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728859AbeLMMbm (ORCPT ); Thu, 13 Dec 2018 07:31:42 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C52CFAC24; Thu, 13 Dec 2018 12:31:39 +0000 (UTC) Date: Thu, 13 Dec 2018 13:31:39 +0100 From: Petr Mladek To: Nicholas Mc Guire Cc: Josh Poimboeuf , Jessica Yu , Jiri Kosina , Miroslav Benes , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] livepatch: handle kzalloc failure Message-ID: <20181213123139.oukmwpkw2yfap6oa@pathway.suse.cz> References: <1544699390-15673-1-git-send-email-hofrat@osadl.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1544699390-15673-1-git-send-email-hofrat@osadl.org> User-Agent: NeoMutt/20170421 (1.8.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 2018-12-13 12:09:49, Nicholas Mc Guire wrote: > kzalloc() return should always be checked - notably in example code > where this may be seen as reference. On failure of allocation > livepatch_fix1_dummy_alloc() should return NULL. > > Signed-off-by: Nicholas Mc Guire > --- > > Problem was located with an experimental coccinelle script > > Patch was compile tested with: x86_64_defconfig + FTRACE=y > FUNCTION_TRACER=y, EXPERT=y, LATENCYTOP=y, SAMPLES=y, SAMPLE_LIVEPATCH=y > (with some unrelated sparse warnings on symbols not being static) > > Patch is against 4.20-rc6 (localversion-next is next-20181213) > > samples/livepatch/livepatch-shadow-fix1.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c > index 49b1355..a0e8f04 100644 > --- a/samples/livepatch/livepatch-shadow-fix1.c > +++ b/samples/livepatch/livepatch-shadow-fix1.c > @@ -89,6 +89,9 @@ struct dummy *livepatch_fix1_dummy_alloc(void) > * pointer to handle resource release. > */ > leak = kzalloc(sizeof(int), GFP_KERNEL); > + if (!leak) > + return NULL; It should be: if (!leak) { kfree(d); return NULL; } Note that The check is not strictly needed in this artificial example because we never read/write any data there. But I agree that we should add the check to promote the the right programming patterns. Best Regards, Petr