From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753054AbaGPVcx (ORCPT ); Wed, 16 Jul 2014 17:32:53 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:34490 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752016AbaGPVcv (ORCPT ); Wed, 16 Jul 2014 17:32:51 -0400 Date: Thu, 17 Jul 2014 00:32:47 +0300 From: Alexey Dobriyan To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH 04/10] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline Message-ID: <20140716213247.GC21290@p183.telecom.by> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.22 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Convert /proc/$PID/cmdline to seq_file interface. XXX This one must be buggy. seq_file buffer is adjustable, so userspace can execute itself with huge command line (which can be arbitrarily long now), then read 1 byte. Voila, whole command line now is in kmalloced/vmalloced memory. Imposing limit is trivial but equally lame to current PAGE_SIZE limit. Signed-off-by: Alexey Dobriyan --- fs/proc/base.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -200,9 +200,17 @@ static int proc_root_link(struct dentry *dentry, struct path *path) return result; } -static int proc_pid_cmdline(struct task_struct *task, char *buffer) +static int proc_pid_cmdline(struct seq_file *m, struct pid_namespace *ns, + struct pid *pid, struct task_struct *task) { - return get_cmdline(task, buffer, PAGE_SIZE); + /* + * Rely on struct seq_operations::show() being called once + * per internal buffer allocation. See single_open(), traverse(). + * + * Rely on internal buffer autoexpansion if it was entirely filled. + */ + m->count += get_cmdline(task, m->buf, m->size); + return 0; } static int proc_pid_auxv(struct seq_file *m, struct pid_namespace *ns, @@ -2567,7 +2575,7 @@ static const struct pid_entry tgid_base_stuff[] = { #ifdef CONFIG_HAVE_ARCH_TRACEHOOK ONE("syscall", S_IRUSR, proc_pid_syscall), #endif - INF("cmdline", S_IRUGO, proc_pid_cmdline), + ONE("cmdline", S_IRUGO, proc_pid_cmdline), ONE("stat", S_IRUGO, proc_tgid_stat), ONE("statm", S_IRUGO, proc_pid_statm), REG("maps", S_IRUGO, proc_pid_maps_operations), @@ -2903,7 +2911,7 @@ static const struct pid_entry tid_base_stuff[] = { #ifdef CONFIG_HAVE_ARCH_TRACEHOOK ONE("syscall", S_IRUSR, proc_pid_syscall), #endif - INF("cmdline", S_IRUGO, proc_pid_cmdline), + ONE("cmdline", S_IRUGO, proc_pid_cmdline), ONE("stat", S_IRUGO, proc_tid_stat), ONE("statm", S_IRUGO, proc_pid_statm), REG("maps", S_IRUGO, proc_tid_maps_operations),