Fix parsing corefile with missing auxv

Closes #2543

Author: Arusekk

pwnlib/elf/corefile.py

@@ -555,6 +555,9 @@ def __init__(self, *a, **kw):
         # Pointer to the entry point
         self.at_entry = 0
 
+        # Pointer to the vdso
+        self.at_sysinfo_ehdr = None
+
         try:
             super(Corefile, self).__init__(*a, **kw)
         except IOError:
@@ -611,6 +614,8 @@ def __init__(self, *a, **kw):
 
             if not self.stack and self.mappings:
                 self.stack = self.mappings[-1].stop
+                if self.mappings[-1].start == 0xffffffffff600000 and len(self.mappings) > 1:
+                    self.stack = self.mappings[-2].stop
 
             if self.stack and self.mappings:
                 for mapping in self.mappings: