[Bug binutils/28166] New: objdump: null ptr dereference on _bfd_elf_mips_get_relocated_section_contents in elfxx-mips.c

[shaohua.li at inf dot ethz.ch]

https://sourceware.org/bugzilla/show_bug.cgi?id=28166

            Bug ID: 28166
           Summary: objdump: null ptr dereference on
                    _bfd_elf_mips_get_relocated_section_contents in
                    elfxx-mips.c
           Product: binutils
           Version: 2.38 (HEAD)
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: shaohua.li at inf dot ethz.ch
  Target Milestone: ---

Created attachment 13577
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13577&action=edit
poc

Hi there,

I found a null pointer dereference with a fuzzer. (See AddressSanitizer report
below)

- binutils version: 2.38(Head), commit af51804103a08cd1e12edc4f4a30eec2c5c4f9e8
- Compiler: clang12
- Platform: Ubuntu 18.04.5 LTS, x86_64
- Reproduce: run `objdump -S poc`

AddressSanitizer report:

==364==ERROR: AddressSanitizer: SEGV on unknown address (pc 0x000001014c7d bp
0x7ffdbfb68190 sp 0x7ffdbfb67ba0 T0)
==364==The signal is caused by a READ memory access.
==364==Hint: this fault was caused by a dereference of a high value address
(see register values below).  Disassemble the provided pc to learn which
register was used.
    #0 0x1014c7d in _bfd_elf_mips_get_relocated_section_contents
/binutils_latest/repo/bfd/elfxx-mips.c:13309:13
    #1 0xae653f in bfd_get_relocated_section_contents
/binutils_latest/repo/bfd/bfd.c:2166:10
    #2 0xb0fe68 in bfd_simple_get_relocated_section_contents
/binutils_latest/repo/bfd/simple.c:298:14
    #3 0xcab59c in read_section /binutils_latest/repo/bfd/./dwarf2.c:582:7
    #4 0xca8237 in _bfd_dwarf2_slurp_debug_info
/binutils_latest/repo/bfd/./dwarf2.c:4737:13
    #5 0xcac7c1 in _bfd_dwarf2_find_nearest_line
/binutils_latest/repo/bfd/./dwarf2.c:4985:9
    #6 0x1013734 in _bfd_mips_elf_find_nearest_line
/binutils_latest/repo/bfd/elfxx-mips.c:13061:7
    #7 0x4e496a in show_line /binutils_latest/repo/binutils/./objdump.c:1784:9
    #8 0x4e0b1f in disassemble_bytes
/binutils_latest/repo/binutils/./objdump.c:2770:6
    #9 0x4dae9a in disassemble_section
/binutils_latest/repo/binutils/./objdump.c:3455:4
    #10 0xb0e04a in bfd_map_over_sections
/binutils_latest/repo/bfd/section.c:1383:5
    #11 0x4d1ae0 in disassemble_data
/binutils_latest/repo/binutils/./objdump.c:3599:3
    #12 0x4cda84 in dump_bfd /binutils_latest/repo/binutils/./objdump.c:5006:5
    #13 0x4ccb9f in display_object_bfd
/binutils_latest/repo/binutils/./objdump.c:5068:7
    #14 0x4ccaa9 in display_any_bfd
/binutils_latest/repo/binutils/./objdump.c:5158:5
    #15 0x4cc65c in display_file
/binutils_latest/repo/binutils/./objdump.c:5179:3
    #16 0x4cb063 in main /binutils_latest/repo/binutils/./objdump.c:5529:6
    #17 0x7ffaf8c830b2 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #18 0x41c61d in _start (/out_bin/objdump+0x41c61d)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /binutils_latest/repo/bfd/elfxx-mips.c:13309:13
in _bfd_elf_mips_get_relocated_section_contents
==364==ABORTING

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