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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 8DBDEC43381 for ; Thu, 14 Mar 2019 13:45:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 685EC2184C for ; Thu, 14 Mar 2019 13:45:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727579AbfCNNpY (ORCPT ); Thu, 14 Mar 2019 09:45:24 -0400 Received: from ivanoab6.miniserver.com ([5.153.251.140]:42502 "EHLO www.kot-begemot.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727356AbfCNNpX (ORCPT ); Thu, 14 Mar 2019 09:45:23 -0400 Received: from jain.kot-begemot.co.uk ([192.168.3.3]) by www.kot-begemot.co.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1h4Qfg-0004DZ-9v; Thu, 14 Mar 2019 13:45:20 +0000 Received: from jain.kot-begemot.co.uk ([192.168.3.3]) by jain.kot-begemot.co.uk with esmtp (Exim 4.89) (envelope-from ) id 1h4Qfe-0002g7-ST; Thu, 14 Mar 2019 13:45:19 +0000 Subject: Re: [PATCH] um: remove uses of variable length arrays To: Bartosz Golaszewski Cc: Jeff Dike , Richard Weinberger , Bartosz Golaszewski , linux-um@lists.infradead.org, Linux Kernel Mailing List References: <20190312133047.16201-1-brgl@bgdev.pl> <56704758-ee74-0e9b-de1c-1dc94deda8d7@cambridgegreys.com> From: Anton Ivanov Message-ID: Date: Thu, 14 Mar 2019 13:45:18 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Clacks-Overhead: GNU Terry Pratchett Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/03/2019 13:33, Bartosz Golaszewski wrote: > śr., 13 mar 2019 o 10:45 Anton Ivanov > napisał(a): >> On 12/03/2019 13:30, Bartosz Golaszewski wrote: >>> From: Bartosz Golaszewski >>> >>> While the affected code is run in user-mode, the build still warns >>> about it. Convert all uses of VLA to dynamic allocations. >>> >>> Signed-off-by: Bartosz Golaszewski >>> --- >>> arch/um/os-Linux/umid.c | 36 +++++++++++++++++++++++++++--------- >>> 1 file changed, 27 insertions(+), 9 deletions(-) >>> >>> diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c >>> index 998fbb445458..e261656fe9d7 100644 >>> --- a/arch/um/os-Linux/umid.c >>> +++ b/arch/um/os-Linux/umid.c >>> @@ -135,12 +135,18 @@ static int remove_files_and_dir(char *dir) >>> */ >>> static inline int is_umdir_used(char *dir) >>> { >>> - char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")]; >>> - char pid[sizeof("nnnnn\0")], *end; >>> + char pid[sizeof("nnnnn\0")], *end, *file; >>> int dead, fd, p, n, err; >>> + size_t filelen; >>> >>> - n = snprintf(file, sizeof(file), "%s/pid", dir); >>> - if (n >= sizeof(file)) { >>> + err = asprintf(&file, "%s/pid", dir); >>> + if (err < 0) >>> + return 0; >>> + >>> + filelen = strlen(file); >>> + >>> + n = snprintf(file, filelen, "%s/pid", dir); >>> + if (n >= filelen) { >>> printk(UM_KERN_ERR "is_umdir_used - pid filename too long\n"); >>> err = -E2BIG; >>> goto out; >>> @@ -185,6 +191,7 @@ static inline int is_umdir_used(char *dir) >>> out_close: >>> close(fd); >>> out: >>> + free(file); >>> return 0; >>> } >>> >>> @@ -210,18 +217,21 @@ static int umdir_take_if_dead(char *dir) >>> >>> static void __init create_pid_file(void) >>> { >>> - char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")]; >>> - char pid[sizeof("nnnnn\0")]; >>> + char pid[sizeof("nnnnn\0")], *file; >>> int fd, n; >>> >>> - if (umid_file_name("pid", file, sizeof(file))) >>> + file = malloc(strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")); >>> + if (!file) >>> return; >>> >>> + if (umid_file_name("pid", file, sizeof(file))) >>> + goto out; >>> + >>> fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644); >>> if (fd < 0) { >>> printk(UM_KERN_ERR "Open of machine pid file \"%s\" failed: " >>> "%s\n", file, strerror(errno)); >>> - return; >>> + goto out; >>> } >>> >>> snprintf(pid, sizeof(pid), "%d\n", getpid()); >>> @@ -231,6 +241,8 @@ static void __init create_pid_file(void) >>> errno); >>> >>> close(fd); >>> +out: >>> + free(file); >>> } >>> >>> int __init set_umid(char *name) >>> @@ -385,13 +397,19 @@ __uml_setup("uml_dir=", set_uml_dir, >>> >>> static void remove_umid_dir(void) >>> { >>> - char dir[strlen(uml_dir) + UMID_LEN + 1], err; >>> + char *dir, err; >>> + >>> + dir = malloc(strlen(uml_dir) + UMID_LEN + 1); >>> + if (!dir) >>> + return; >>> >>> sprintf(dir, "%s%s", uml_dir, umid); >>> err = remove_files_and_dir(dir); >>> if (err) >>> os_warn("%s - remove_files_and_dir failed with err = %d\n", >>> __func__, err); >>> + >>> + free(dir); >>> } >>> >>> __uml_exitcall(remove_umid_dir); >>> >> Thanks for bringing it up. It helped me notice that this is actually broken. >> >> PID can be more than 5 digits nowdays. >> >> -- > Do you want to take this patch anyway and then apply the fix for the > array on top of that or do you prefer it be fixed before that? > > Bart > I am OK to take it as is and have the PID length fixed after that. -- Anton R. Ivanov Cambridgegreys Limited. Registered in England. Company Number 10273661 https://www.cambridgegreys.com/