json_normalize does not work correctly with MSAN build

CURRENT_TEST: main.func_json

mysqltest: At line 2480: query 'INSERT INTO num_table values('15')' failed: <Unknown> (2013): Lost connection to server during query

…

==44786==WARNING: MemorySanitizer: use-of-uninitialized-value

    #0 0x564a01b5fdef in json_normalize_number /mariadb/11/strings/json_normalize.c:155:22

    #1 0x564a01b634b8 in json_norm_value_number_init /mariadb/11/strings/json_normalize.c:517:8

    #2 0x564a01b634b8 in json_norm_value_init /mariadb/11/strings/json_normalize.c:586:10

    #3 0x564a01b605ef in json_norm_build /mariadb/11/strings/json_normalize.c:771:8

    #4 0x564a01b605ef in json_normalize /mariadb/11/strings/json_normalize.c:835:8

    #5 0x564a000021ab in json_get_normalized_string(st_json_engine_t*, String*, int*) /mariadb/11/sql/json_schema_helper.cc:85:9

    #6 0x5649fffe1a78 in Json_schema_const::validate(st_json_engine_t const*, unsigned char const*, unsigned char const*) /mariadb/11/sql/json_schema.cc:447:7

    #7 0x5649fffb8bfc in Item_func_json_schema_valid::val_int() /mariadb/11/sql/item_jsonfunc.cc:4757:25

    #8 0x5649ffc185b7 in TABLE::verify_constraints(bool) /mariadb/11/sql/table.cc:6447:26

    #9 0x5649ffc18053 in TABLE_LIST::view_check_option(THD*, bool) /mariadb/11/sql/table.cc:6420:17

    #10 0x5649ff57af73 in mysql_insert(THD*, TABLE_LIST*, List<Item>&, List<List<Item>>&, List<Item>&, List<Item>&, enum_duplicates, bool, select_result*) /mariadb/11/sql/sql_insert.cc:1130:29

    #11 0x5649ff6c4e90 in mysql_execute_command(THD*, bool) /mariadb/11/sql/sql_parse.cc:4449:10

    #12 0x5649ff69dd01 in mysql_parse(THD*, char*, unsigned int, Parser_state*) /mariadb/11/sql/sql_parse.cc:7760:18

    #13 0x5649ff694454 in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool) /mariadb/11/sql/sql_parse.cc:1892:7

    #14 0x5649ff69f4ca in do_command(THD*, bool) /mariadb/11/sql/sql_parse.cc:1405:17

    #15 0x5649ffd662cc in do_handle_one_connection(CONNECT*, bool) /mariadb/11/sql/sql_connect.cc:1416:11

    #16 0x5649ffd658a7 in handle_one_connection /mariadb/11/sql/sql_connect.cc:1318:5

    #17 0x564a00625167 in pfs_spawn_thread /mariadb/11/storage/perfschema/pfs.cc:2201:3

    #18 0x7f5d1dc10fd3 in start_thread nptl/pthread_create.c:442:8

    #19 0x7f5d1dc9081f in clone misc/../sysdeps/unix/sysv/linux/x86_64/clone.S:100

  Memory was marked as uninitialized

    #0 0x5649fe71c90d in __msan_allocated_memory (/dev/shm/11/sql/mariadbd+0x10dc90d) (BuildId: 1237e4b564f291c6)

    #1 0x564a019118da in my_malloc /mariadb/11/mysys/my_malloc.c:114:7

diff --git a/strings/json_normalize.c b/strings/json_normalize.c

index 0b7f172dae6..2c66c712e81 100644

--- a/strings/json_normalize.c

+++ b/strings/json_normalize.c

@@ -147,13 +147,16 @@ json_normalize_number(DYNAMIC_STRING *out, const char *str, size_t str_len)

   magnitude = (long)(j - 1);

-  /* skip the . */

-  if (str[i] == '.')

-    ++i;

+  if (i < str_len)

+  {

+    /* skip the . */

+    if (str[i] == '.')

+      ++i;

-  /* grab rest of digits before the E */

-  for (; i < str_len && str[i] != 'e' && str[i] != 'E'; ++i)

-    buf[j++] = str[i];

+    /* grab rest of digits before the E */

+    for (; i < str_len && str[i] != 'e' && str[i] != 'E'; ++i)

+      buf[j++] = str[i];

+  }

   /* trim trailing zeros */

   for (k = j - 1; k && buf[k] == '0'; --k, --j)

@@ -187,7 +190,7 @@ json_normalize_number(DYNAMIC_STRING *out, const char *str, size_t str_len)

   err|= dynstr_append_mem(out, STRING_WITH_LEN("E"));

-  if (str[i] == 'e' || str[i] == 'E')

+  if (i < str_len && (str[i] == 'e' || str[i] == 'E'))

   {

     char *endptr = NULL;

     /* skip the [eE] */