This is a note to let you know that I've just added the patch titled

Revert "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%3Ba=su...

The filename of the patch is: revert-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 stable@vger.kernel.org know about it.

From 779f4e1c6c7c661db40dfebd6dd6bda7b5f88aa3 Mon Sep 17 00:00:00 2001

From: Kees Cook keescook@chromium.org Date: Tue, 12 Dec 2017 11:28:38 -0800 Subject: Revert "exec: avoid RLIMIT_STACK races with prlimit()" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

From: Kees Cook keescook@chromium.org

commit 779f4e1c6c7c661db40dfebd6dd6bda7b5f88aa3 upstream.

This reverts commit 04e35f4495dd560db30c25efca4eecae8ec8c375.

SELinux runs with secureexec for all non-"noatsecure" domain transitions, which means lots of processes end up hitting the stack hard-limit change that was introduced in order to fix a race with prlimit(). That race fix will need to be redesigned.

Reported-by: Laura Abbott labbott@redhat.com Reported-by: Tomáš Trnka trnka@scm.com Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- fs/exec.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)

--- a/fs/exec.c +++ b/fs/exec.c @@ -1340,15 +1340,10 @@ 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 - * races from other threads changing the limits. This also - * must be protected from races with prlimit() calls. + * needing to clean up the change on failure. */ - 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/revert-exec-avoid-rlimit_stack-races-with-prlimit.patch queue-4.14/string.h-workaround-for-increased-stack-usage.patch queue-4.14/arm64-fix-config_debug_wx-address-reporting.patch