Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [day] [month] [year] [list]
Date: Mon, 10 Apr 2017 07:28:26 +0000
From: "Agostino Sarubbo" <ago@...too.org>
To: "oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>
Subject: elfutils: heap-based buffer overflow in ebl_object_note_type_name (eblobjnotetypename.c)

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

A fuzz on eu-readelf showed an heap overflow. Will follow a feedback from upstream:

Nice find. The issue is with notes that have a zero sized name (and also no descriptor data at the end of a note section).
“The system reserves note information with no name (namesz==0) and with a zero-length name (name[0]==’\0′) but currently defines no types. All other names must have at least one non-null character.”
So we must explicitly check for namesz == 0 before using the name data in the note.

The complete ASan output:

# eu-readelf -a $FILE
==29866==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60200000ef9c at pc 0x7f910ac17150 bp 0x7fff92f7ed90 sp 0x7fff92f7e540
READ of size 1 at 0x60200000ef9c thread T0
    #0 0x7f910ac1714f  (/usr/lib/gcc/x86_64-pc-linux-gnu/6.3.0/libasan.so.3+0x4514f)
    #1 0x4f63a7 in ebl_object_note_type_name /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libebl/eblobjnotetypename.c:48
    #2 0x461251 in handle_notes_data /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:9372
    #3 0x47209d in handle_notes /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:9455
    #4 0x47209d in process_elf_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:916
    #5 0x47ae65 in process_dwflmod /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:690
    #6 0x7f910a730094 in dwfl_getmodules /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libdwfl/dwfl_getmodules.c:82
    #7 0x4365f2 in process_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:789
    #8 0x405e50 in main /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:305
    #9 0x7f9108d4e78f in __libc_start_main (/lib64/libc.so.6+0x2078f)
    #10 0x406cd8 in _start (/usr/bin/eu-readelf+0x406cd8)

0x60200000ef9c is located 0 bytes to the right of 12-byte region [0x60200000ef90,0x60200000ef9c)
allocated by thread T0 here:
    #0 0x7f910ac94288 in malloc (/usr/lib/gcc/x86_64-pc-linux-gnu/6.3.0/libasan.so.3+0xc2288)
    #1 0x7f910a10af48 in convert_data /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:166
    #2 0x7f910a10af48 in __libelf_set_data_list_rdlock /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:434
    #3 0x7f910a10c9ba in __elf_getdata_rdlock /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:541
    #4 0x7f910a10ccae in elf_getdata /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libelf/elf_getdata.c:559
    #5 0x471fe7 in handle_notes /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:9455
    #6 0x471fe7 in process_elf_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:916
    #7 0x47ae65 in process_dwflmod /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:690
    #8 0x7f910a730094 in dwfl_getmodules /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/libdwfl/dwfl_getmodules.c:82
    #9 0x4365f2 in process_file /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:789
    #10 0x405e50 in main /tmp/portage/dev-libs/elfutils-0.168/work/elfutils-0.168/src/readelf.c:305
    #11 0x7f9108d4e78f in __libc_start_main (/lib64/libc.so.6+0x2078f)

SUMMARY: AddressSanitizer: heap-buffer-overflow (/usr/lib/gcc/x86_64-pc-linux-gnu/6.3.0/libasan.so.3+0x4514f) 
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 00[04]fa fa 00 02 fa fa 00 02 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
==29866==ABORTING
Affected version:
0.168

Fixed version:
0.169 (not released atm)

Commit fix:
https://sourceware.org/ml/elfutils-devel/2017-q1/msg00111.html

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

CVE:
CVE-2017-7608

Reproducer:
https://github.com/asarubbo/poc/blob/master/00226-elfutils-heapoverflow-ebl_object_note_type_name

Timeline:
2017-03-24: 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:
https://blogs.gentoo.org/ago/2017/04/03/elfutils-heap-based-buffer-overflow-in-ebl_object_note_type_name-eblobjnotetypename-c/

--
Agostino Sarubbo
Gentoo Linux Developer


Powered by blists - more mailing lists

Your e-mail address:

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Powered by Openwall GNU/*/Linux - Powered by OpenVZ