elfutils: heap-based buffer overflow in check_sysv_hash (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
==14428==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60b00000aff4 at pc 0x00000040b36b bp 0x7ffe1e25ef20 sp 0x7ffe1e25ef18
READ of size 4 at 0x60b00000aff4 thread T0
    #0 0x40b36a in check_sysv_hash /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:2020
    #1 0x40b36a in check_hash /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:2315
    #2 0x422e73 in check_sections /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:4118
    #3 0x42961f in process_elf_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:4697
    #4 0x42961f in process_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:242
    #5 0x402d33 in main /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/elflint.c:175
    #6 0x7f7a318a878f in __libc_start_main (/lib64/libc.so.6+0x2078f)
    #7 0x403498 in _start (/usr/bin/eu-elflint+0x403498)

0x60b00000aff7 is located 0 bytes to the right of 103-byte region [0x60b00000af90,0x60b00000aff7)
allocated by thread T0 here:
    #0 0x7f7a32f95288 in malloc (/usr/lib/gcc/x86_64-pc-linux-gnu/6.3.0/libasan.so.3+0xc2288)
    #1 0x7f7a32bf1b46 in convert_data /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:166
    #2 0x7f7a32bf1b46 in __libelf_set_data_list_rdlock /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:434
    #3 0x7f7a32bf2662 in __elf_getdata_rdlock /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:541
    #4 0x7f7a32bf2776 in elf_getdata /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:559
    #5 0x7f7a32c1e035 in elf32_getchdr /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf32_getchdr.c:72
    #6 0x7f7a32c1e55c 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 0x7f7a318a878f 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:2020 in check_sysv_hash
Shadow bytes around the buggy address:
  0x0c167fff95a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c167fff95b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c167fff95c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c167fff95d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c167fff95e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c167fff95f0: fa fa 00 00 00 00 00 00 00 00 00 00 00 00[07]fa
  0x0c167fff9600: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c167fff9610: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c167fff9620: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c167fff9630: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c167fff9640: 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
==14428==ABORTING

Affected version:
0.168

Fixed version:
0.169 (not released atm)

Commit fix:
https://sourceware.org/ml/elfutils-devel/2017-q1/msg00131.html

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

CVE:
CVE-2017-7612

Reproducer:
https://github.com/asarubbo/poc/blob/master/00235-elfutils-heapoverflow-check_sysv_hash

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_sysv_hash (elflint.c)

This entry was posted in advisories, security. Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.