FAILED: patch "[PATCH] exec: Copy oldsighand->action under spin-lock" failed to apply to 4.9-stable tree

FAILED: patch "[PATCH] exec: Copy oldsighand->action under spin-lock" failed to apply to 4.9-stable tree

[gregkh]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

Possible dependencies:

5bf2fedca8f5 ("exec: Copy oldsighand->action under spin-lock")
021691559245 ("exec: Factor unshare_sighand out of de_thread and call it separately")
d036bda7d0e7 ("sched/core: Convert sighand_struct.count to refcount_t")
06e62a46bbba ("fork: don't copy inconsistent signal handler state to child")
2a1f062a4acf ("sched/headers: Move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>")
c3edc4010e9d ("sched/headers: Move task_struct::signal and task_struct::sighand types and accessors into <linux/sched/signal.h>")
11701c676836 ("sched/headers: Move task->mm coredumping related defines and methods from <linux/sched.h> to <linux/sched/coredump.h>")
dea38c74cb92 ("sched/headers: Move loadavg related definitions from <linux/sched.h> to <linux/sched/loadavg.h>")
9164bb4a18df ("sched/headers: Prepare to move 'init_task' and 'init_thread_union' from <linux/sched.h> to <linux/sched/task.h>")
589ee62844e0 ("sched/headers: Prepare to remove the <linux/mm_types.h> dependency from <linux/sched.h>")
f361bf4a66c9 ("sched/headers: Prepare for the reduction of <linux/sched.h>'s signal API dependency")
68db0cf10678 ("sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h>")
299300258d1b ("sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>")
ef8bd77f332b ("sched/headers: Prepare for new header dependencies before moving code to <linux/sched/hotplug.h>")
b17b01533b71 ("sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>")
370c91355c76 ("sched/headers: Prepare for new header dependencies before moving code to <linux/sched/nohz.h>")
03441a3482a3 ("sched/headers: Prepare for new header dependencies before moving code to <linux/sched/stat.h>")
fd7712337ff0 ("sched/headers: Prepare to remove the <linux/gfp.h> include from <linux/sched.h>")
174cd4b1e5fb ("sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>")
037741a6d4ab ("sched/headers: Prepare for the removal of <linux/rtmutex.h> from <linux/sched.h>")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5bf2fedca8f59379025b0d52f917b9ddb9bfe17e Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Mon, 7 Jun 2021 15:54:27 +0200
Subject: [PATCH] exec: Copy oldsighand->action under spin-lock

unshare_sighand should only access oldsighand->action
while holding oldsighand->siglock, to make sure that
newsighand->action is in a consistent state.

Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: stable@vger.kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/AM8PR10MB470871DEBD1DED081F9CC391E4389@AM8PR10MB4708.EURPRD10.PROD.OUTLOOK.COM

diff --git a/fs/exec.c b/fs/exec.c
index 349a5da91efe..32dc8cf5fceb 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1197,11 +1197,11 @@ static int unshare_sighand(struct task_struct *me)
 			return -ENOMEM;
 
 		refcount_set(&newsighand->count, 1);
-		memcpy(newsighand->action, oldsighand->action,
-		       sizeof(newsighand->action));
 
 		write_lock_irq(&tasklist_lock);
 		spin_lock(&oldsighand->siglock);
+		memcpy(newsighand->action, oldsighand->action,
+		       sizeof(newsighand->action));
 		rcu_assign_pointer(me->sighand, newsighand);
 		spin_unlock(&oldsighand->siglock);
 		write_unlock_irq(&tasklist_lock);