re.c: make MatchData#hash check the MatchData is already initialized

Make sure that the MatchData is already initialized by calling
match_check() first so as not to dereference NULL.

1 files changed, 3 insertions, 1 deletions

diff --git a/re.c b/re.c
index 0536aa6d8e..6574d9fcdf 100644
--- a/re.c
+++ b/re.c
@@ -2948,8 +2948,10 @@ static VALUE
 match_hash(VALUE match)
 {
     const struct re_registers *regs;
-    st_index_t hashval = rb_hash_start(rb_str_hash(RMATCH(match)->str));
+    st_index_t hashval;
 
+    match_check(match);
+    hashval = rb_hash_start(rb_str_hash(RMATCH(match)->str));
     rb_hash_uint(hashval, reg_hash(RMATCH(match)->regexp));
     regs = RMATCH_REGS(match);
     hashval = rb_hash_uint(hashval, regs->num_regs);