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

kernel/signal.c: protect the SIGNAL_UNKILLABLE tasks from !sig_kernel_only() signals

to the 4.9-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: kernel-signal.c-protect-the-signal_unkillable-tasks-from-sig_kernel_only-signals.patch and it can be found in the queue-4.9 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 ac25385089f673560867eb5179228a44ade0cfc1 Mon Sep 17 00:00:00 2001

From: Oleg Nesterov oleg@redhat.com Date: Fri, 17 Nov 2017 15:30:04 -0800 Subject: kernel/signal.c: protect the SIGNAL_UNKILLABLE tasks from !sig_kernel_only() signals

From: Oleg Nesterov oleg@redhat.com

commit ac25385089f673560867eb5179228a44ade0cfc1 upstream.

Change sig_task_ignored() to drop the SIG_DFL && !sig_kernel_only() signals even if force == T. This simplifies the next change and this matches the same check in get_signal() which will drop these signals anyway.

Link: http://lkml.kernel.org/r/20171103184227.GC21036@redhat.com Signed-off-by: Oleg Nesterov oleg@redhat.com Tested-by: Kyle Huey me@kylehuey.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- kernel/signal.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/signal.c +++ b/kernel/signal.c @@ -72,7 +72,7 @@ static int sig_task_ignored(struct task_ handler = sig_handler(t, sig);

if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && - handler == SIG_DFL && !force) + handler == SIG_DFL && !(force && sig_kernel_only(sig))) return 1;

return sig_handler_ignored(handler, sig);

Patches currently in stable-queue which might be from oleg@redhat.com are

queue-4.9/kernel-signal.c-remove-the-no-longer-needed-signal_unkillable-check-in-complete_signal.patch queue-4.9/kernel-signal.c-protect-the-signal_unkillable-tasks-from-sig_kernel_only-signals.patch queue-4.9/kernel-acct.c-fix-the-acct-needcheck-check-in-check_free_space.patch queue-4.9/kernel-signal.c-protect-the-traced-signal_unkillable-tasks-from-sigkill.patch