elfutils: heap-based buffer overflow in check_symtab_shndx (elflint.c)

Description:
elfutils is a set of libraries/utilities to handle ELF objects (drop in replacement for libelf).

A fuzz on eu-elflint showed an heap overflow.

The complete ASan output:

# eu-elflint -d $FILE
==14342==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60200000efd0 at pc 0x0000004267ec bp 0x7ffdf36a7ad0 sp 0x7ffdf36a7ac8
READ of size 4 at 0x60200000efd0 thread T0
    #0 0x4267eb in check_symtab_shndx /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:1961
    #1 0x4267eb in check_sections /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:4114
    #2 0x42961f in process_elf_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:4697
    #3 0x42961f in process_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:242
    #4 0x402d33 in main /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:175
    #5 0x7f625ef4678f in __libc_start_main (/lib64/libc.so.6+0x2078f)
    #6 0x403498 in _start (/usr/bin/eu-elflint+0x403498)

0x60200000efd2 is located 0 bytes to the right of 2-byte region [0x60200000efd0,0x60200000efd2)
allocated by thread T0 here:
    #0 0x7f6260633288 in malloc (/usr/lib/gcc/x86_64-pc-linux-gnu/6.3.0/libasan.so.3+0xc2288)
    #1 0x7f626028fb46 in convert_data /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:166
    #2 0x7f626028fb46 in __libelf_set_data_list_rdlock /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:434
    #3 0x7f6260290662 in __elf_getdata_rdlock /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:541
    #4 0x7f6260290776 in elf_getdata /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:559
    #5 0x7f62602bc035 in elf32_getchdr /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf32_getchdr.c:72
    #6 0x7f62602bc55c in gelf_getchdr /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/gelf_getchdr.c:52
    #7 0x420edf in check_sections /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:3911
    #8 0x42961f in process_elf_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:4697
    #9 0x42961f in process_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:242
    #10 0x402d33 in main /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:175
    #11 0x7f625ef4678f in __libc_start_main (/lib64/libc.so.6+0x2078f)

SUMMARY: AddressSanitizer: heap-buffer-overflow /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:1961 in check_symtab_shndx
Shadow bytes around the buggy address:
  0x0c047fff9da0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9db0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9dc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9dd0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9de0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c047fff9df0: fa fa fa fa fa fa fa fa fa fa[02]fa fa fa 00 01
  0x0c047fff9e00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e40: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==14342==ABORTING

Affected version:
0.168

Fixed version:
0.169 (not released atm)

Commit fix:
https://sourceware.org/ml/elfutils-devel/2017-q1/msg00129.html

Credit:
This bug was discovered by Agostino Sarubbo of Gentoo.

CVE:
CVE-2017-7611

Reproducer:
https://github.com/asarubbo/poc/blob/master/00234-elfutils-heapoverflow-check_symtab_shndx

Timeline:
2017-03-27: bug discovered and reported to upstream
2017-04-04: blog post about the issue
2017-04-09: CVE assigned

Note:
This bug was found with American Fuzzy Lop.

Permalink:

elfutils: heap-based buffer overflow in check_symtab_shndx (elflint.c)

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