Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [day] [month] [year] [list]
Date: Wed, 01 Feb 2017 10:18:08 +0100
From: Agostino Sarubbo <ago@...too.org>
To: oss-security@...ts.openwall.com
Subject: pax-utils: scanelf: out of bounds read in scanelf_file_textrel (scanelf.c)

Description:
pax-utils is a set of tools that check files for security relevant properties.

A fuzz on scanelf exposed an out-of bound read. It was reported to vapier 
which fixed the issue immediately.
Unfortunately I can’t get a symbolized ASan stacktrace, so I will show only 
the useful part of both asan and gdb.

# scanelf -s '*' -axetrnibSDIYZB $FILE
==1853==ERROR: AddressSanitizer: unknown-crash on address 0x7f4099d25008 at pc 
0x00000053586e bp 0x7fff335cb8b0 sp 0x7fff335cb8a8
READ of size 8 at 0x7f4099d25008 thread T0
    #0 0x53586d  (/usr/bin/scanelf+0x53586d)
    #1 0x51f526  (/usr/bin/scanelf+0x51f526)
    #2 0x51b97e  (/usr/bin/scanelf+0x51b97e)
    #3 0x51ad43  (/usr/bin/scanelf+0x51ad43)
    #4 0x51922e  (/usr/bin/scanelf+0x51922e)
    #5 0x7f4098afd61f  (/lib64/libc.so.6+0x2061f)
    #6 0x41a008  (/usr/bin/scanelf+0x41a008) 

(gdb) bt
#8  0x000000000053586e in scanelf_file_textrel (elf=, found_textrel=) at 
scanelf.c:560
#9  0x000000000051f527 in scanelf_elfobj (elf=) at scanelf.c:1536
#10 0x000000000051b97f in scanelf_elf (filename=0x7fffffffe50e 
"/tmp/afl/scanelf/report/crashes/2.crashes", fd=, len=) at scanelf.c:1612
#11 scanelf_fileat (dir_fd=, filename=, st_cache=) at scanelf.c:1679
#12 0x000000000051ad44 in scanelf_dirat (dir_fd=, path=) at scanelf.c:1713
#13 0x000000000051922f in scanelf_dir (path=) at scanelf.c:1763
#14 parseargs (argc=5, argv=0x7fffffffe258) at scanelf.c:2273
#15 main (argc=5, argv=) at scanelf.c:2361

Affected version:
1.2

Fixed version:
1.2.1

Commit fix:
https://github.com/gentoo/pax-utils/commit/95e5489534ac9e9324c5096286899b688e19ae00

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

CVE:
N/A

Reproducer:
https://github.com/asarubbo/poc/blob/master/00132-pax-utils-scanelf-oobread-scanelf_file_textrel

Timeline:
2017-01-23: bug discovered and reported to upstream
2017-01-24: upstream realeased a patch and 1.2.1
2017-02-01: blog post about the issue

Note:
This bug was found with American Fuzzy Lop.
I’d suggest to go to 1.2.2 because of a functionality bug(s) in 1.2.1

Permalink:
https://blogs.gentoo.org/ago/2017/02/01/pax-utils-scanelf-out-of-bounds-read-in-scanelf_file_textrel-scanelf-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.

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