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List:       oss-security
Subject:    [oss-security] binutils: NULL pointer dereference in scan_unit_for_symbols (dwarf2.c)
From:       "Agostino Sarubbo" <ago () gentoo ! org>
Date:       2017-09-30 17:02:40
Message-ID: 991074.005930813-sendEmail () localhost
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Description:
binutils is a set of tools necessary to build programs.

The complete ASan output of the issue:

# nm -A -a -l -S -s --special-syms --synthetic --with-symbol-versions -D $FILE
==491==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f6e3316d573 bp \
0x7ffda2ee9e50 sp 0x7ffda2ee9c60 T0) ==491==The signal is caused by a READ memory access.
==491==Hint: address points to the zero page.
    #0 0x7f6e3316d572 in scan_unit_for_symbols \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:3213:13  #1 0x7f6e331769e4 \
in comp_unit_maybe_decode_line_info \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:3617:9  #2 0x7f6e331769e4 \
in comp_unit_find_line /var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:3643 \
#3 0x7f6e331707c8 in _bfd_dwarf2_find_nearest_line \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:4601:11  #4 0x7f6e330b120b \
in _bfd_elf_find_line /var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/elf.c:8694:10  \
#5 0x517c83 in print_symbol \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1003:9  #6 0x51542d in \
print_symbols /var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1084:7  #7 \
0x51542d in display_rel_file \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1200  #8 0x510f56 in \
display_file /var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1318:7  #9 \
0x50faae in main /var/tmp/portage/sys-devel/binutils-9999/work/binutils/binutils/nm.c:1792:12  \
#10 0x7f6e31ff6680 in __libc_start_main \
/var/tmp/portage/sys-libs/glibc-2.23-r4/work/glibc-2.23/csu/../csu/libc-start.c:289  #11 \
0x41ac18 in _init (/usr/x86_64-pc-linux-gnu/binutils-bin/git/nm+0x41ac18)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV \
/var/tmp/portage/sys-devel/binutils-9999/work/binutils/bfd/dwarf2.c:3213:13 in \
scan_unit_for_symbols ==491==ABORTING

Affected version:
2.29.51.20170921 and maybe past releases

Fixed version:
N/A

Commit fix:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=0d76029f92182c3682d8be2c833d45bc9a2068fe


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

CVE:
CVE-2017-14940

Reproducer:
https://github.com/asarubbo/poc/blob/master/00369-binutils-NULLptr-scan_unit_for_symbols

Timeline:
2017-09-21: bug discovered and reported to upstream
2017-09-24: upstream released a patch
2017-09-26: blog post about the issue
2017-09-29: 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/2017/09/26/binutils-null-pointer-dereference-in-scan_unit_for_symbols-dwarf2-c


--
Agostino Sarubbo
Gentoo Linux Developer


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