From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47139) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WAdlo-0004Jj-Ab for qemu-devel@nongnu.org; Tue, 04 Feb 2014 06:02:32 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WAdlf-0001dp-TK for qemu-devel@nongnu.org; Tue, 04 Feb 2014 06:02:24 -0500 Received: from mail-pb0-x229.google.com ([2607:f8b0:400e:c01::229]:53329) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WAdlf-0001dU-MM for qemu-devel@nongnu.org; Tue, 04 Feb 2014 06:02:15 -0500 Received: by mail-pb0-f41.google.com with SMTP id up15so8339741pbc.0 for ; Tue, 04 Feb 2014 03:02:14 -0800 (PST) Message-ID: <52F0C8BA.7020709@gmail.com> Date: Tue, 04 Feb 2014 19:02:18 +0800 From: Chen Gang MIME-Version: 1.0 References: <52EF68CA.9060604@gmail.com> <20140203103429.GB10408@redhat.com> <52EF71DC.3000309@gmail.com> In-Reply-To: <52EF71DC.3000309@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] hw/9pfs/virtio-9p-local.c: use snprintf() instead of sprintf() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: aneesh.kumar@linux.vnet.ibm.com, aliguori@amazon.com, QEMU Developers On 02/03/2014 06:39 PM, Chen Gang wrote: > On 02/03/2014 06:34 PM, Daniel P. Berrange wrote: >> On Mon, Feb 03, 2014 at 06:00:42PM +0800, Chen Gang wrote: >>> We can not assume "'path' + 'ctx->fs_root'" must be less than MAX_PATH, >>> so need use snprintf() instead of sprintf(). >>> >>> And also recommend to use ARRAY_SIZE instead of hard code macro for an >>> array size in snprintf(). >> >> In the event that there is overflow this will cause the data to be >> truncated, potentially causing QEMU to access the wrong file on the >> host. Both snprintf and sprintf are really bad because of their >> use of fixed buffers. Better to change it to g_strdup_printf which >> dynamically allocates buffers. >> After check the details, I guess we can not change to g_strdup_printf or others (e.g. v9fs_string_*). v9fs need use "mkdir, remove ..." which have MAX_PATH limitation. So if the combined path is longer than MAX_PATH, before it passes to "mkdir, remove ...", it has to be truncated just like what rpath() has done. So for me, we have to still use snprintf() instead of sprintf(), but really need provide the related comments under each snprintf(). > > That sounds reasonable to me, I will send patch v2 for it. > > > Thanks. > Thanks. -- Chen Gang Open, share and attitude like air, water and life which God blessed