timer/debug: Change /proc/timer_list from 0444 to 0400

BugLink: https://bugs.launchpad.net/bugs/1811252

[ Upstream commit 8e7df2b5 ]

While it uses %pK, there's still few reasons to read this file
as non-root.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

kernel/time/timer_list.c

@@ -399,7 +399,7 @@ static int __init init_timer_list_procfs(void)
 {
 	struct proc_dir_entry *pe;
 
-	pe = proc_create("timer_list", 0444, NULL, &timer_list_fops);
+	pe = proc_create("timer_list", 0400, NULL, &timer_list_fops);
 	if (!pe)
 		return -ENOMEM;
 	return 0;