From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759596Ab0JVS51 (ORCPT ); Fri, 22 Oct 2010 14:57:27 -0400 Received: from kroah.org ([198.145.64.141]:34514 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758948Ab0JVS5S (ORCPT ); Fri, 22 Oct 2010 14:57:18 -0400 X-Mailbox-Line: From gregkh@clark.site Fri Oct 22 11:52:36 2010 Message-Id: <20101022185236.453073855@clark.site> User-Agent: quilt/0.48-11.2 Date: Fri, 22 Oct 2010 11:52:16 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Roland McGrath , Chuck Ebbert Subject: [102/103] execve: make responsive to SIGKILL with large arguments In-Reply-To: <20101022185455.GA9114@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.35-stable review patch. If anyone has any objections, please let us know. ------------------ From: Roland McGrath commit 9aea5a65aa7a1af9a4236dfaeb0088f1624f9919 upstream. An execve with a very large total of argument/environment strings can take a really long time in the execve system call. It runs uninterruptibly to count and copy all the strings. This change makes it abort the exec quickly if sent a SIGKILL. Note that this is the conservative change, to interrupt only for SIGKILL, by using fatal_signal_pending(). It would be perfectly correct semantics to let any signal interrupt the string-copying in execve, i.e. use signal_pending() instead of fatal_signal_pending(). We'll save that change for later, since it could have user-visible consequences, such as having a timer set too quickly make it so that an execve can never complete, though it always happened to work before. Signed-off-by: Roland McGrath Reviewed-by: KOSAKI Motohiro Cc: Chuck Ebbert Signed-off-by: Linus Torvalds --- fs/exec.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/fs/exec.c +++ b/fs/exec.c @@ -377,6 +377,9 @@ static int count(char __user * __user * argv++; if (i++ >= max) return -E2BIG; + + if (fatal_signal_pending(current)) + return -ERESTARTNOHAND; cond_resched(); } } @@ -420,6 +423,10 @@ static int copy_strings(int argc, char _ while (len > 0) { int offset, bytes_to_copy; + if (fatal_signal_pending(current)) { + ret = -ERESTARTNOHAND; + goto out; + } cond_resched(); offset = pos % PAGE_SIZE;