1 files changed, 17 insertions, 0 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index eca34503f178..f9821a3374e9 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3095,6 +3095,14 @@ t_probe_next(struct seq_file *m, loff_t *pos)
                 hnd = &iter->probe_entry->hlist;
 
         hash = iter->probe->ops.func_hash->filter_hash;
+
+        /*
+         * A probe being registered may temporarily have an empty hash
+         * and it's at the end of the func_probes list.
+         */
+        if (!hash || hash == EMPTY_HASH)
+                return NULL;
+
         size = 1 << hash->size_bits;
 
  retry:
@@ -4320,12 +4328,21 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr,
 
         mutex_unlock(&ftrace_lock);
 
+        /*
+         * Note, there's a small window here that the func_hash->filter_hash
+         * may be NULL or empty. Need to be carefule when reading the loop.
+         */
         mutex_lock(&probe->ops.func_hash->regex_lock);
 
         orig_hash = &probe->ops.func_hash->filter_hash;
         old_hash = *orig_hash;
         hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, old_hash);
 
+        if (!hash) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
         ret = ftrace_match_records(hash, glob, strlen(glob));
 
         /* Nothing found? */