kprobes: Lock kprobe_mutex while showing kprobe_blacklist

Lock kprobe_mutex while showing kprobe_blacklist to prevent updating the
kprobe_blacklist.

Signed-off-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Alexandre Chartre <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

Author: mhiramat

kernel/kprobes.c

@@ -2420,6 +2420,7 @@ static const struct file_operations debugfs_kprobes_operations = {
 /* kprobes/blacklist -- shows which functions can not be probed */
 static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
 {
+	mutex_lock(&kprobe_mutex);
 	return seq_list_start(&kprobe_blacklist, *pos);
 }
 
@@ -2446,10 +2447,15 @@ static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
 	return 0;
 }
 
+static void kprobe_blacklist_seq_stop(struct seq_file *f, void *v)
+{
+	mutex_unlock(&kprobe_mutex);
+}
+
 static const struct seq_operations kprobe_blacklist_seq_ops = {
 	.start = kprobe_blacklist_seq_start,
 	.next  = kprobe_blacklist_seq_next,
-	.stop  = kprobe_seq_stop,	/* Reuse void function */
+	.stop  = kprobe_blacklist_seq_stop,
 	.show  = kprobe_blacklist_seq_show,
 };