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List:       oss-security
Subject:    [oss-security] binutils: NULL pointer dereference in concat_filename (dwarf2.c) (INCOMPLETE FIX FOR 
From:       "Agostino Sarubbo" <ago () gentoo ! org>
Date:       2017-10-27 20:25:11
Message-ID: 93509.5195631845-sendEmail () localhost
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Description:
binutils is a set of tools necessary to build programs.

The commit fix for this issue says:

The PR22200 fuzzer testcase found one way to put NULLs into .debug_line file tables. PR22205 \
finds another. So mitre considers this an incomplete fix.

The complete ASan output of the issue:

# nm -A -a -l -S -s --special-syms --synthetic --with-symbol-versions -D $FILE
==19042==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x0000006a76a6 bp \
0x7ffde0afde30 sp 0x7ffde0afde00 T0) ==19042==The signal is caused by a READ memory access.
==19042==Hint: address points to the zero page.
    #0 0x6a76a5 in concat_filename \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:1601:8  #1 0x696ff3 in \
decode_line_info /var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:2265:44  \
#2 0x6a2d36 in comp_unit_maybe_decode_line_info \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:3651:26  #3 0x6a2d36 in \
comp_unit_find_line /var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:3686  \
#4 0x6a0369 in _bfd_dwarf2_find_nearest_line \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:4798:11  #5 0x5f332e in \
_bfd_elf_find_line /var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/elf.c:8695:10  #6 \
0x5176a3 in print_symbol \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1003:9  #7 0x514e4d in \
print_symbols /var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1084:7  #8 \
0x514e4d in display_rel_file \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1200  #9 0x510976 in \
display_file /var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1318:7  #10 \
0x50f4ce in main /var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1792:12  \
#11 0x7f6c6d793680 in __libc_start_main \
/var/tmp/portage/sys-libs/glibc-2.23-r4/work/glibc-2.23/csu/../csu/libc-start.c:289  #12 \
0x41a638 in chmod (/usr/x86_64-pc-linux-gnu/binutils-bin/git/nm+0x41a638)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:1601:8 in concat_filename \
==19042==ABORTING

Affected version:
2.29.51.20170925 and maybe past releases

Fixed version:
N/A

Commit fix:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=a54018b72d75abf2e74bf36016702da06399c1d9


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

CVE:
CVE-2017-15939

Reproducer:
https://github.com/asarubbo/poc/blob/master/00380-binutils-NULLptr-concat_filename

Timeline:
2017-09-25: bug discovered and reported to upstream
2017-09-26: upstream released a patch
2017-10-24: blog post about the issue
2017-10-27: CVE assigned

Note:
This bug was found with American Fuzzy Lop.
This bug was identified with bare metal servers donated by Packet. This work is also supported \
by the Core Infrastructure Initiative.

Permalink:
https://blogs.gentoo.org/ago/2017/10/24/binutils-null-pointer-dereference-in-concat_filename-dwarf2-c-incomplete-fix-for-cve-2017-15023/


--
Agostino Sarubbo
Gentoo Linux Developer


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