Building of dbg binary fails when there are no section headers

[zwilcox]

I'm getting the following error when the script tries to build the new dbg binary:

Traceback (most recent call last):
  File "/my/path/ghidra2dwarf/src/ghidra2dwarf.py", line 521, in <module>
    add_sections_to_elf(exe_path, out_path, sections)
  File "/my/path/ghidra2dwarf/src/elf.py", line 195, in add_sections_to_elf
    out = e.generate_updated_elf()
  File "/my/path/ghidra2dwarf/src/elf.py", line 155, in generate_updated_elf
    section_headers = self.extract_section_headers()
  File "/my/path/ghidra2dwarf/src/elf.py", line 140, in extract_section_headers
    self.section_names = self.extract_section(self.section_headers[h.shstrndx])
IndexError: index out of range: 0
ghidra2dwarf.py> Finished!

It appears this occurs when there are no section headers in the elf binary:

readelf -h /another/path/squashfs-root/bin/busybox
ELF Header:
  Magic:   7f 45 4c 46 01 02 01 00 00 00 00 00 00 00 00 00
  Class:                             ELF32
  Data:                              2's complement, big endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           MIPS R3000
  Version:                           0x1
  Entry point address:               0x403220
  Start of program headers:          52 (bytes into file)
  Start of section headers:          0 (bytes into file)
  Flags:                             0x70001007, noreorder, pic, cpic, o32, mips32r2
  Size of this header:               52 (bytes)
  Size of program headers:           32 (bytes)
  Number of program headers:         8
  Size of section headers:           0 (bytes)
  Number of section headers:         0
  Section header string table index: 0

Would it be reasonable to add the following to elf.py

if self.section_headers:
  self.section_names = self.extract_section(self.section_headers[h.shstrndx])

[zwilcox]

This seemed to fix it:

diff --git a/src/elf.py b/src/elf.py
index 63f21f7..e64bdde 100644
--- a/src/elf.py
+++ b/src/elf.py
@@ -92,6 +92,7 @@ class Elf:
        def __init__(self, bytes):
                self.bytes = bytearray(bytes)
                self.extract_ident()
+               self.section_names = bytearray()
                bits = '64' if self.ident.elf_class == ElfClass.ELFCLASS64 else '32'
                #bits = '64' if ElfClass[self.ident.elf_class] == ElfClass.ELFCLASS64 else '32'
                endianness = 'le' if self.ident.elf_data == ElfData.ELFDATA2LSB else 'be'
@@ -137,7 +138,10 @@ class Elf:
                h = self.extract_header()
                for i in range(h.shnum):
                        self.section_headers.append(self._dump_struct(ElfSectionHeader, h.shoff + i * h.shentsize))
-               self.section_names = self.extract_section(self.section_headers[h.shstrndx])
+
+               if self.section_headers:
+                       self.section_names = self.extract_section(self.section_headers[h.shstrndx])
+

Done.
ELF saved to /another/path//bin/busybox_dbg
C source saved to /another/path//bin/busybox_dbg.c
ghidra2dwarf.py> Finished!

Thoughts?

[nneonneo]

Thanks for the useful fixes in this and other issues. They’re clearly needed, and if @meowmeowxw is still around I think they’d be happy to have them.

I still keep an eye on this repo from time to time, but I don’t have committer access to it. If you wanted to, you could submit a PR either here or over at my fork; I’ll pull the fixes into my fork so they’re at least available in some form, and hopefully eventually they can get upstreamed here.

[meowmeowxw]

Hey @nneonneo , @zwilcox If you open PRs I will test and merge in the next days. I'm available to merge bug fixes or small code refactoring patches