The patch for MDEV-8466 revealed a bug in str2my_decimal,

which did not return a correct "end_of_num" pointer in case of character sets with mbminlen>1 (ucs2, utf16, utf16le, utf32). The bug caused sporadic test failures on BuildBot, as well "uninitialized memory read" errors in valgrind builds.

Author: Alexander Barkov

sql/my_decimal.cc

@@ -243,21 +243,21 @@ int str2my_decimal(uint mask, const char *from, uint length,
  const char **end_ptr)
 {
  int err;
- char buff[STRING_BUFFER_USUAL_SIZE];
- String tmp(buff, sizeof(buff), &my_charset_bin);
  if (charset->mbminlen > 1)
  {
+ StringBuffer<STRING_BUFFER_USUAL_SIZE> tmp;
  uint dummy_errors;
  tmp.copy(from, length, charset, &my_charset_latin1, &dummy_errors);
- from= tmp.ptr();
- length= tmp.length();
- charset= &my_charset_bin;
+ char *end= (char*) tmp.end();
+ err= string2decimal(tmp.ptr(), (decimal_t*) decimal_value, &end);
+ *end_ptr= from + charset->mbminlen * (size_t) (end - tmp.ptr());
+ }
+ else
+ {
+ char *end= (char*) from + length;
+ err= string2decimal(from, (decimal_t*) decimal_value, &end);
+ *end_ptr= end;
  }
- char *end= (char*) from + length;
- err= string2decimal((char *)from, (decimal_t*) decimal_value, &end);
- if (charset->mbminlen > 1)
- end= (char *) from + charset->mbminlen * (size_t) (end - buff);
- *end_ptr= end;
  check_result_and_overflow(mask, err, decimal_value);
  return err;
 }