False positive on LocationParser.attribute_has_location()

[sevaa]

The description of DW_AT_member_location changed between DWARFv2 and DWARFv3:

v2, section 5.5.4:

If the member entry is defined in the structure or class body, it has a
DW_AT_data_member_location attribute whose value is a location description

v3, section 5.5.6:

If a data member is defined in a structure, union or class, the corresponding member entry has a DW_AT_data_member_location attribute whose value describes the location of that member relative to the base address of the structure, union, or class that most closely encloses the member declaration. If that value is a constant, it is the offset in bytes from the beginning of the innermost enclosing structure, union or class to the beginning of the data member. Otherwise, the value must be a location description.

The case of DW_AT_data_member_location containing an integer constant is not handled by pyelftools - the method LocationParser.attribute_has_location() returns True, and it shouldn't.

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I have a crash report where an attribute with the following data:

AttributeValue(name='DW_AT_data_member_location', form='DW_FORM_data1', value=0, raw_value=0, offset=402, indirection_length=0)

is being interpreted as a location list pointer (LocationParser.parse_from_attribute() tries to parse it), which in turn exceptions, because the binary doesn't contain a loclist section (self.location_lists is None).

[sevaa]

While at it, also fixed a false negative in attribute_has_location() for the DWARFv5 counterparts of GNU_call_xxx attributes.

[sevaa]

Done.

[eliben]

Thanks!