title: Check to see if a pointer could possibly be valid in a core dump with gdb
body: <p>I have a core file from a linux c++ program, and it crashed with a segmentation fault.  Looking at the backtrace and code, I find one pointer/object that could be garbage.  The pointer address is <code>this=0x62900000f200</code>, so is there a way I can determine if that could possibly be a valid address using GDB?</p>
  <p>What I'm hoping for is a way to get GDB to tell me what allocated memory regions are, or what memory the core dump contains.  I know accuracy will be low because its somewhat likely that a slightly mangled pointer could still point to &quot;valid&quot; memory, but hopefully there is a way to identify pointers that can't possibly be valid.</p>
  <p>I have seen questions asking if a pointer &quot;is valid&quot; and I know the complexity of determining if a pointer as been free'd already, or if its point to the wrong object, etc, but that is not what I'm asking.  I just want a test that would say, &quot;This core contains all memory from address 0x01 to 0x50, and your pointer is 0x70, so its obviously not valid.&quot;</p>