[patch V4 part 1 15/36] kprobes: Lock kprobe_mutex while showing kprobe_blacklist

[Thomas Gleixner]

From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>

Lock kprobe_mutex while showing kprobe_blacklist to prevent updating the
kprobe_blacklist.

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/158523417665.24735.10253198878535635600.stgit@devnote2

---
 kernel/kprobes.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2426,6 +2426,7 @@ static const struct file_operations debu
 /* 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);
 }
 
@@ -2452,10 +2453,15 @@ static int kprobe_blacklist_seq_show(str
 	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,
 };