Security vulnerability in MySQL/MariaDB sql/password.c

password.c

typedef char my_bool;

/*
  Check that scrambled message corresponds to the password; the function
  is used by server to check that recieved reply is authentic.

RETURN VALUE
  0  password is correct
  !0  password is invalid
*/
my_bool
check_scramble(const char *scramble_arg, const char *message,
               const uint8 *hash_stage2)
{
  SHA1_CONTEXT sha1_context;
  uint8 buf[SHA1_HASH_SIZE];
  uint8 hash_stage2_reassured[SHA1_HASH_SIZE];

  mysql_sha1_reset(&sha1_context);
  /* create key to encrypt scramble */
  mysql_sha1_input(&sha1_context, (const uint8*)message, SCRAMBLE_LENGTH);
  mysql_sha1_input(&sha1_context, hash_stage2, SHA1_HASH_SIZE);
  mysql_sha1_result(&sha1_context, buf);
  /* encrypt scramble */
  my_crypt((char*)buf, buf, (const uchar*)scramble_arg, SCRAMBLE_LENGTH);
  /* now buf supposedly contains hash_stage1: so we can get hash_stage2 */
  mysql_sha1_reset(&sha1_context);
  mysql_sha1_input(&sha1_context, buf, SHA1_HASH_SIZE);
  mysql_sha1_result(&sha1_context, hash_stage2_reassured);
  return memcmp(hash_stage2, hash_stage2_reassured, SHA1_HASH_SIZE);
}