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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 A7FCFC388F3 for ; Sat, 28 Sep 2019 21:24:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C6B8214DE for ; Sat, 28 Sep 2019 21:24:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569705840; bh=IL2VVcFyxpeEUNpyOhzjpMAkldnUFCjDXmLJjSwk0b4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=wU99vmR13rE/fI46N5311M/49TNp5SUG7+sjvY9yDpZDLkBO2q8zK2TlfpE2jtnlk lpDk0UmOU+OUii7jsojV25uO78Oz/1UYGomKAmNPhvfRBY7BeylzUpqrMUtk4sdMzu P/bM3QLBPc2SHnnOMdVFhv+H6n8qiZMbFeGNuWcc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728777AbfI1VX7 (ORCPT ); Sat, 28 Sep 2019 17:23:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:42056 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726581AbfI1VX7 (ORCPT ); Sat, 28 Sep 2019 17:23:59 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 AFAEC2082F; Sat, 28 Sep 2019 21:23:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569705837; bh=IL2VVcFyxpeEUNpyOhzjpMAkldnUFCjDXmLJjSwk0b4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=wLdl2VGnUe1bttx+zoWYTFG0bVC3xiy9wTHUhXVGdxu0oGh+c2V1lcRZUegpXKI4O bDk12tLvcuBPRlRc+QaY9NVwiuEUXyWwrjig3MiTd2pzE1GZdfzJTxAKehjSZOqBTf G9t6No8G87XcrxeJ2aBKM9W7gl2v6Wr2VIa1YDGY= Date: Sat, 28 Sep 2019 14:23:56 -0700 From: Andrew Morton To: Dan Carpenter Cc: Greg Kroah-Hartman , Andy Shevchenko , tglx@linutronix.de, Enrico Weigelt , Kate Stewart , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [PATCH] mm, vmpressure: Fix a signedness bug in vmpressure_register_event() Message-Id: <20190928142356.932cff0ad6c17f4a18edc80f@linux-foundation.org> In-Reply-To: <20190925110449.GO3264@mwanda> References: <20190925110449.GO3264@mwanda> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 25 Sep 2019 14:04:49 +0300 Dan Carpenter wrote: > The "mode" and "level" variables are enums and in this context GCC will > treat them as unsigned ints so the error handling is never triggered. > > I also removed the bogus initializer because it isn't required any more > and it's sort of confusing. > A bit picky of me, but it's an eyesore to assign an int to an enum, then compare the casted enum to an int then copy the enum back to an int. How about doing it this way? Only copy the int to the enum once we know it's within range? --- a/mm/vmpressure.c~mm-vmpressure-fix-a-signedness-bug-in-vmpressure_register_event-fix +++ a/mm/vmpressure.c @@ -375,20 +375,18 @@ int vmpressure_register_event(struct mem /* Find required level */ token = strsep(&spec, ","); - level = match_string(vmpressure_str_levels, VMPRESSURE_NUM_LEVELS, token); - if ((int)level < 0) { - ret = level; + ret = match_string(vmpressure_str_levels, VMPRESSURE_NUM_LEVELS, token); + if (ret < 0) goto out; - } + level = ret; /* Find optional mode */ token = strsep(&spec, ","); if (token) { - mode = match_string(vmpressure_str_modes, VMPRESSURE_NUM_MODES, token); - if ((int)mode < 0) { - ret = mode; + ret = match_string(vmpressure_str_modes, VMPRESSURE_NUM_MODES, token); + if (ret < 0) goto out; - } + mode = ret; } ev = kzalloc(sizeof(*ev), GFP_KERNEL); _