oss-security - xar: NULL pointer dereference in xar

Follow @Openwall on Twitter for new release announcements and other news

[<prev] [next>] [day] [month] [year] [list]

Date: Mon, 10 Jul 2017 09:11:48 +0000
From: "Agostino Sarubbo" <ago@...too.org>
To: "oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>
Subject: xar: NULL pointer dereference in xar_unserialize (archive.c)

Description:
xar is an easily extensible archive format.

The complete ASan output of the issue:

# xar -t -f $FILE
==7615==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000008 (pc 0x7f71a859ebd6 bp 0x7fffd8ace150 sp 0x7fffd8acde80 T0)
==7615==The signal is caused by a WRITE memory access.
==7615==Hint: address points to the zero page.
    #0 0x7f71a859ebd5 in xar_unserialize /var/tmp/portage/app-arch/xar-1.6.1-r1/work/xar-1.6.1/lib/archive.c:1767:27
    #1 0x7f71a859ebd5 in xar_open /var/tmp/portage/app-arch/xar-1.6.1-r1/work/xar-1.6.1/lib/archive.c:340
    #2 0x5139ee in list /var/tmp/portage/app-arch/xar-1.6.1-r1/work/xar-1.6.1/src/xar.c:1492:6
    #3 0x5139ee in main /var/tmp/portage/app-arch/xar-1.6.1-r1/work/xar-1.6.1/src/xar.c:2666
    #4 0x7f71a76a2680 in __libc_start_main /tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
    #5 0x41af38 in _init (/usr/bin/xar+0x41af38)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /var/tmp/portage/app-arch/xar-1.6.1-r1/work/xar-1.6.1/lib/archive.c:1767:27 in xar_unserialize
==7615==ABORTING
Affected version:
1.6.1

Fixed version:
N/A

Commit fix:
N/A

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

CVE:
CVE-2017-11124

Reproducer:
https://github.com/asarubbo/poc/blob/master/00288-xar-nullptr-xar_unserialize

Timeline:
2017-06-17: bug discovered and reported to upstream
2017-06-28: blog post about the issue
2017-07-10: CVE assigned

Note:
This bug was found with American Fuzzy Lop.

Permalink:
https://blogs.gentoo.org/ago/2017/06/28/xar-null-pointer-dereference-in-xar_unserialize-archive-c/

--
Agostino Sarubbo
Gentoo Linux Developer

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

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.