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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 EFBCBC49ED7 for ; Fri, 20 Sep 2019 06:04:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C32AE20882 for ; Fri, 20 Sep 2019 06:04:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568959474; bh=FMHYLNhnUIWX/Ad7Hx9zHh7rSIMaDyP2houL0wEpfnY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=yrXNZs2i8cXMXRx3QWE1Fg3wJGX7kmlmjYHqGyi9SqLWDLcfhUrMQyWAZlhH+0Qeh /fAhqOfZUERCz6z6I7V1OYU7q3R+vB8gXmFDxYCbbZtqASMTgEWALdBY8XIqJP/8YL Yz6ZmFWFaOaqMtxjpC7DlpmxkFyMsJVBwSe+P4/8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2408208AbfITGEc (ORCPT ); Fri, 20 Sep 2019 02:04:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:46036 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2408197AbfITGEc (ORCPT ); Fri, 20 Sep 2019 02:04:32 -0400 Received: from localhost (unknown [145.15.244.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B14812086A; Fri, 20 Sep 2019 06:04:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568959471; bh=FMHYLNhnUIWX/Ad7Hx9zHh7rSIMaDyP2houL0wEpfnY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C4EWCyGCf0Pe4SOOTvruW2VA7hJDuNTJQvwqSPAm8TeTTyPgb3NzE2UD/Vxx7hhH8 5EvAoib85g/KwuzD4n4t55sirjnnO++lnuM/bVmIL9LJJ1O91OHOmwZxErmI1YOWFR DUfktYSjkx6Ez0rYZ583u/BoyYnuLjiqAS6Dauy0= Date: Fri, 20 Sep 2019 08:04:26 +0200 From: Greg KH To: Nicolas Pitre Cc: Xiaoming Ni , penberg@cs.helsinki.fi, jslaby@suse.com, textshell@uchuujin.de, sam@ravnborg.org, daniel.vetter@ffwll.ch, mpatocka@redhat.com, ghalat@redhat.com, linux-kernel@vger.kernel.org, yangyingliang@huawei.com, yuehaibing@huawei.com, zengweilin@huawei.com Subject: Re: [PATCH] tty:vt: Add check the return value of kzalloc to avoid oops Message-ID: <20190920060426.GA473496@kroah.com> References: <1568884695-56789-1-git-send-email-nixiaoming@huawei.com> <20190919092933.GA2684163@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 19, 2019 at 10:56:15PM -0400, Nicolas Pitre wrote: > On Thu, 19 Sep 2019, Greg KH wrote: > > > On Thu, Sep 19, 2019 at 05:18:15PM +0800, Xiaoming Ni wrote: > > > Using kzalloc() to allocate memory in function con_init(), but not > > > checking the return value, there is a risk of null pointer references > > > oops. > > > > > > Signed-off-by: Xiaoming Ni > > > > We keep having this be "reported" :( > > Something probably needs to be "communicated" about that. I know, but it's also kind of fun to see what these "automated" checkers find, sometimes the resulting patches almost work properly :) This one is really close, I think if the likely/unlikely gets cleaned up, it is viable. > > > vc_cons[currcons].d = vc = kzalloc(sizeof(struct vc_data), GFP_NOWAIT); > > > + if (unlikely(!vc)) { > > > + pr_warn("%s:failed to allocate memory for the %u vc\n", > > > + __func__, currcons); > > > + break; > > > + } > > > > At init, this really can not happen. Have you see it ever happen? > > This is maybe too subtle a fact. The "communication" could be done with > some GFP_WONTFAIL flag, and have the allocator simply pannic() if it > ever fails. That's a good idea to do as well. thanks, greg k-h