From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:36746 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753147AbdLDIsU (ORCPT ); Mon, 4 Dec 2017 03:48:20 -0500 Subject: Patch "exec: avoid RLIMIT_STACK races with prlimit()" has been added to the 4.14-stable tree To: keescook@chromium.org, akpm@linux-foundation.org, ben.hutchings@codethink.co.uk, gregkh@linuxfoundation.org, james.l.morris@oracle.com, jslaby@suse.cz, luto@kernel.org, oleg@redhat.com, serge@hallyn.com, spender@grsecurity.net, torvalds@linux-foundation.org Cc: , From: Date: Mon, 04 Dec 2017 09:48:23 +0100 Message-ID: <151237730392147@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled exec: avoid RLIMIT_STACK races with prlimit() to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: exec-avoid-rlimit_stack-races-with-prlimit.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 04e35f4495dd560db30c25efca4eecae8ec8c375 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 29 Nov 2017 16:10:51 -0800 Subject: exec: avoid RLIMIT_STACK races with prlimit() From: Kees Cook commit 04e35f4495dd560db30c25efca4eecae8ec8c375 upstream. While the defense-in-depth RLIMIT_STACK limit on setuid processes was protected against races from other threads calling setrlimit(), I missed protecting it against races from external processes calling prlimit(). This adds locking around the change and makes sure that rlim_max is set too. Link: http://lkml.kernel.org/r/20171127193457.GA11348@beast Fixes: 64701dee4178e ("exec: Use sane stack rlimit under secureexec") Signed-off-by: Kees Cook Reported-by: Ben Hutchings Reported-by: Brad Spengler Acked-by: Serge Hallyn Cc: James Morris Cc: Andy Lutomirski Cc: Oleg Nesterov Cc: Jiri Slaby Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/exec.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/exec.c +++ b/fs/exec.c @@ -1340,10 +1340,15 @@ void setup_new_exec(struct linux_binprm * avoid bad behavior from the prior rlimits. This has to * happen before arch_pick_mmap_layout(), which examines * RLIMIT_STACK, but after the point of no return to avoid - * needing to clean up the change on failure. + * races from other threads changing the limits. This also + * must be protected from races with prlimit() calls. */ + task_lock(current->group_leader); if (current->signal->rlim[RLIMIT_STACK].rlim_cur > _STK_LIM) current->signal->rlim[RLIMIT_STACK].rlim_cur = _STK_LIM; + if (current->signal->rlim[RLIMIT_STACK].rlim_max > _STK_LIM) + current->signal->rlim[RLIMIT_STACK].rlim_max = _STK_LIM; + task_unlock(current->group_leader); } arch_pick_mmap_layout(current->mm); Patches currently in stable-queue which might be from keescook@chromium.org are queue-4.14/exec-avoid-rlimit_stack-races-with-prlimit.patch