Description:
libpcre is a perl-compatible regular expression library.
A fuzz on pcre2 via pcre2test revealed an overflow in that command-line utility.
# pcre2test -d -i -32 $FILE
==30932==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61100000a000 at pc 0x7f2d8c3aea0f bp 0x7ffeea6b6e20 sp 0x7ffeea6b6e18
WRITE of size 4 at 0x61100000a000 thread T0
#0 0x7f2d8c3aea0e in pcre2_get_error_message_32 /tmp/portage/dev-libs/libpcre2-10.23/work/pcre2-10.23/src/pcre2_error.c:318:13
#1 0x53b7c5 in process_pattern /tmp/portage/dev-libs/libpcre2-10.23/work/pcre2-10.23/src/pcre2test.c:5169:3
#2 0x513846 in main /tmp/portage/dev-libs/libpcre2-10.23/work/pcre2-10.23/src/pcre2test.c:7839:10
#3 0x7f2d8b37478f in __libc_start_main /tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
#4 0x41d5b8 in _init (/usr/bin/pcre2test+0x41d5b8)
0x61100000a000 is located 0 bytes to the right of 256-byte region [0x611000009f00,0x61100000a000)
allocated by thread T0 here:
#0 0x4d6378 in malloc /tmp/portage/sys-devel/llvm-3.9.1-r1/work/llvm-3.9.1.src/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:64
#1 0x54c522 in to32 /tmp/portage/dev-libs/libpcre2-10.23/work/pcre2-10.23/src/pcre2test.c:2911:27
#2 0x53962e in process_pattern /tmp/portage/dev-libs/libpcre2-10.23/work/pcre2-10.23/src/pcre2test.c:4998:43
#3 0x513846 in main /tmp/portage/dev-libs/libpcre2-10.23/work/pcre2-10.23/src/pcre2test.c:7839:10
#4 0x7f2d8b37478f in __libc_start_main /tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
SUMMARY: AddressSanitizer: heap-buffer-overflow /tmp/portage/dev-libs/libpcre2-10.23/work/pcre2-10.23/src/pcre2_error.c:318:13 in pcre2_get_error_message_32
Shadow bytes around the buggy address:
0x0c227fff93b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c227fff93c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c227fff93d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c227fff93e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c227fff93f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c227fff9400:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c227fff9410: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c227fff9420: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c227fff9430: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c227fff9440: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c227fff9450: 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
==30932==ABORTING
Affected version:
10.23
Fixed version:
N/A
Commit fix:
https://vcs.pcre.org/pcre2/code/trunk/src/pcre2test.c?r1=692&r2=697
Credit:
This bug was discovered by Agostino Sarubbo of Gentoo.
CVE:
CVE-2017-8786
Reproducer:
https://github.com/asarubbo/poc/blob/master/00220-pcre2-heapoverflow-pcre2_get_error_message_32
Timeline:
2017-03-17: bug discovered and reported to upstream
2017-03-21: upstream released a patch
2017-04-29: blog post about the issue
2017-05-05: CVE assigned
Note:
This bug was found with American Fuzzy Lop.
Permalink: