From a15d0e267a8a429cf2a2a4358080666ee2260526 Mon Sep 17 00:00:00 2001
From: Andrew Bromwich <a.bromwich@gmail.com>
Date: Wed, 20 Apr 2022 22:30:35 +1000
Subject: [PATCH] [flori/json] Fix parser bug for empty string allocation

When `HAVE_RB_ENC_INTERNED_STR` is enabled it is possible to
pass through a null pointer to `rb_enc_interned_str` resulting
in a segfault

Fixes #495

https://github.com/flori/json/commit/b59368a8c2
---
 ext/json/parser/parser.c      | 8 ++++++++
 ext/json/parser/parser.rl     | 8 ++++++++
 test/json/json_parser_test.rb | 1 +
 3 files changed, 17 insertions(+)

diff --git a/ext/json/parser/parser.c b/ext/json/parser/parser.c
index b7de60ddfb..8b860c4101 100644
--- a/ext/json/parser/parser.c
+++ b/ext/json/parser/parser.c
@@ -2363,9 +2363,17 @@ static VALUE json_string_unescape(char *string, char *stringEnd, int intern, int
 	char buf[4];
 
 	if (bufferSize > MAX_STACK_BUFFER_SIZE) {
+# ifdef HAVE_RB_ENC_INTERNED_STR
+		bufferStart = buffer = ALLOC_N(char, bufferSize ? bufferSize : 1);
+# else
 		bufferStart = buffer = ALLOC_N(char, bufferSize);
+# endif
 	} else {
+# ifdef HAVE_RB_ENC_INTERNED_STR
+		bufferStart = buffer = ALLOCA_N(char, bufferSize ? bufferSize : 1);
+# else
 		bufferStart = buffer = ALLOCA_N(char, bufferSize);
+# endif
 	}
 
 	while (pe < stringEnd) {
diff --git a/ext/json/parser/parser.rl b/ext/json/parser/parser.rl
index 15e6b929f5..2dee80ee3b 100644
--- a/ext/json/parser/parser.rl
+++ b/ext/json/parser/parser.rl
@@ -462,9 +462,17 @@ static VALUE json_string_unescape(char *string, char *stringEnd, int intern, int
     char buf[4];
 
     if (bufferSize > MAX_STACK_BUFFER_SIZE) {
+# ifdef HAVE_RB_ENC_INTERNED_STR
+      bufferStart = buffer = ALLOC_N(char, bufferSize ? bufferSize : 1);
+# else
       bufferStart = buffer = ALLOC_N(char, bufferSize);
+# endif
     } else {
+# ifdef HAVE_RB_ENC_INTERNED_STR
+      bufferStart = buffer = ALLOCA_N(char, bufferSize ? bufferSize : 1);
+# else
       bufferStart = buffer = ALLOCA_N(char, bufferSize);
+# endif
     }
 
     while (pe < stringEnd) {
diff --git a/test/json/json_parser_test.rb b/test/json/json_parser_test.rb
index dce693e548..00b254fc6a 100644
--- a/test/json/json_parser_test.rb
+++ b/test/json/json_parser_test.rb
@@ -84,6 +84,7 @@ class JSONParserTest < Test::Unit::TestCase
     assert_equal({ "a" => 23 }, parse('  { "a"  : 23  } '))
     assert_equal({ "a" => 0.23 }, parse(' { "a"  :  0.23 }  '))
     assert_equal({ "a" => 0.23 }, parse('  {  "a"  :  0.23  }  '))
+    assert_equal({ "" => 123 }, parse('{"":123}'))
   end
 
   def test_parse_numbers