Bug #99906 Got heap-use-after-free error when using asan

• Submitted: 17 Jun 2020 2:41
• Modified: 17 Jun 2020 3:10
• Reporter: Zhang JiYang
• Status: Closed
• Category: MySQL Server
• Severity: S3 (Non-critical)
• Version: 5.6.*
• OS: Any
• CPU Architecture: Any

[17 Jun 2020 2:41] Zhang JiYang

Description:
See the following codes, it leads to a heap-use-after-free error from asan, although it does not affect the normal operation of the MySQL.

mysys_ssl/my_getopt.cc
static void init_one_value(...)
{
   ...
   my_free(*pstr);
   *pstr= my_strdup((char*) (intptr) value, MYF(MY_WME));
   ...
}

mysys/my_malloc.c
char *my_strdup(const char *from, myf my_flags)
{
  char *ptr;
  size_t length= strlen(from)+1;
  if ((ptr= (char*) my_malloc(length, my_flags)))
    memcpy(ptr, from, length);
  return ptr;
}

How to repeat:
NULL

[17 Jun 2020 3:10] Zhang JiYang

It seems that it happens when setting default value of Sys_var_charptr by my_strdup.