Merge pull request #13 from vsoch/try/update-again

updating elf.py with upstream master

cle/backends/elf/elf.py

@@ -8,7 +8,7 @@
 import elftools
 from elftools.elf import elffile, sections, dynamic, enums
 from elftools.dwarf import callframe
-from elftools.common.exceptions import ELFError, DWARFError
+from elftools.common.exceptions import ELFError, DWARFError, ELFParseError
 from elftools.dwarf.dwarf_expr import DWARFExprParser
 from elftools.dwarf.descriptions import describe_form_class, describe_attr_value, set_global_machine_arch
 from elftools.dwarf.dwarfinfo import DWARFInfo
@@ -616,8 +616,11 @@ def _load_line_info(self, dwarf):
         """
         for cu in dwarf.iter_CUs():
             comp_dir = '.'
-            die = cu.get_top_DIE()
-
+            try:
+                die = cu.get_top_DIE()
+            except KeyError:
+                # pyelftools is not very resilient
+                continue
             if 'DW_AT_comp_dir' in die.attributes:
                 comp_dir = die.attributes['DW_AT_comp_dir'].value.decode()
 
@@ -626,16 +629,14 @@ def _load_line_info(self, dwarf):
             if "DW_AT_stmt_list" in die.attributes:
                 del die.attributes["DW_AT_stmt_list"]
 
-            # Added because this fails sometimes, along with lineprog.get_entries()
             try:
                 lineprog = dwarf.line_program_for_CU(cu)
-                if lineprog is None:
-                    continue
-                entries = lineprog.get_entries()
-            except Exception as e:
+            except ELFParseError:
+                continue
+            if lineprog is None:
                 continue
             file_cache = {}
-            for line in entries:
+            for line in lineprog.get_entries():
                 if line.state is None:
                     continue
                 if line.state.file in file_cache:
@@ -721,13 +722,17 @@ def parse_die_types(die):
         for cu in dwarf.iter_CUs():
             expr_parser = DWARFExprParser(cu.structs)
 
-            # scan the whole die tree for DW_TAG_base_type and DW_TAG_typedef
-            for die in cu.iter_DIEs():                
-                if die.tag == "DW_TAG_base_type":
-                    var_type = VariableType.read_from_die(die)
-                    if var_type is not None:
-                        type_list[die.offset] = var_type
-                parse_die_types(die)
+            # scan the whole die tree for DW_TAG_base_type
+            try:
+                for die in cu.iter_DIEs():
+                    if die.tag == "DW_TAG_base_type":
+                        var_type = VariableType.read_from_die(die)
+                        if var_type is not None:
+                            type_list[die.offset] = var_type
+                    parse_die_types(die)
+            except KeyError:
+                # pyelftools is not very resilient - we need to catch KeyErrors here
+                continue
 
             # Provide type information to the corpus
             self.corpus.type_die_lookup = type_die_lookup

cle/backends/elf/elfcore.py

@@ -64,6 +64,8 @@ def __init__(self, *args, executable=None, remote_file_mapping=None, remote_file
 
         self.__reload_children()
 
+        self._remote_file_mapper = None
+
     @staticmethod
     def is_compatible(stream):
         stream.seek(0)

tests/test_dwarf_resiliency.py

@@ -0,0 +1,18 @@
+# pylint:disable=no-self-use,missing-class-docstring
+import os
+from unittest import TestCase, main
+
+import cle
+
+
+TESTS_BASE = os.path.join(os.path.dirname(os.path.realpath(__file__)),
+                                  os.path.join('..', '..', 'binaries', 'tests'))
+
+class TestDwarfResiliency(TestCase):
+    def test_dwarf_pyelftools_keyerrors(self):
+        binary_path = os.path.join(TESTS_BASE, "i386", "dwarf_resiliency_0")
+        _ = cle.Loader(binary_path, auto_load_libs=False, load_debug_info=True)
+
+
+if __name__ == "__main__":
+    main()