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 <mhiramat@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134059.571125195@linutronix.de

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 2625c24..570d608 100644 (file)
--- a/kernel/kprobes.c
+++ b/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,
 };