https://bugs.exim.org/show_bug.cgi?id=2482
Bug ID: 2482
Summary: Heap buffer overflow vulnerability in GETCHARINCTEST()
(pcre2_match.c)
Product: PCRE
Version: 10.34 (PCRE2)
Hardware: x86-64
OS: All
Status: NEW
Severity: security
Priority: medium
Component: Code
Assignee: ph10@???
Reporter: clickwithsk@???
CC: pcre-dev@???
Created attachment 1237
-->
https://bugs.exim.org/attachment.cgi?id=1237&action=edit
Crash input file that triggers the bug
The latest version of PCRE is prone to a Heap Overflow vulnerability which can
be triggered using a crafted regular expression. It could allow a remote
attacker to obtain sensitive information, or cause denial of service. This
vulnerability occurs because the library fails to perform adequate
boundary-checks on user-supplied data in GETCHARINCTEST() (pcre2_match.c),
which leads to a heap buffer overflow, causing an out of bounds memory read,
and subsequently resulting into a crash.
====================
Output of ASAN compiled library (-fsanitize=address)
Run as: ./pcre2test crash_file (attached herewith)
---------------------
==4636==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x629000004200
at pc 0x5555555f527f bp 0x7fffffff7b60 sp 0x7fffffff7b50
READ of size 1 at 0x629000004200 thread T0
#0 0x5555555f527e in match src/pcre2_match.c:2211
#1 0x5555555f527e in pcre2_match_8 src/pcre2_match.c:6968
#2 0x555555576c41 in process_data src/pcre2test.c:7537
#3 0x55555557cd61 in main src/pcre2test.c:9004
#4 0x7ffff681db96 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
#5 0x55555557dbf9 in _start
(pcre-10.34-RC1/pcre2test-addrsan-fno-omit-gdwarf-g3+0x29bf9)
0x629000004200 is located 0 bytes to the right of 16384-byte region
[0x629000000200,0x629000004200)
allocated by thread T0 here:
#0 0x7ffff6ef8f40 in realloc
(/usr/lib/x86_64-linux-gnu/libasan.so.4+0xdef40)
#1 0x555555574899 in process_data src/pcre2test.c:6652
#2 0x55555557cd61 in main src/pcre2test.c:9004
#3 0x7ffff681db96 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
SUMMARY: AddressSanitizer: heap-buffer-overflow src/pcre2_match.c:2211 in match
Shadow bytes around the buggy address:
0x0c527fff87f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c527fff8800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c527fff8810: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c527fff8820: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c527fff8830: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c527fff8840:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c527fff8850: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c527fff8860: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c527fff8870: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c527fff8880: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c527fff8890: 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
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
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
==4636==ABORTING
=====================
valgrind output:
valgrind -v --leak-check=full ./pcre2test crash_file
--------------------
==6892==
==6892== HEAP SUMMARY:
==6892== in use at exit: 117,816 bytes in 14 blocks
==6892== total heap usage: 25 allocs, 11 frees, 124,446 bytes allocated
==6892==
==6892== Searching for pointers to 14 not-freed blocks
==6892== Checked 75,648 bytes
==6892==
==6892== LEAK SUMMARY:
==6892== definitely lost: 0 bytes in 0 blocks
==6892== indirectly lost: 0 bytes in 0 blocks
==6892== possibly lost: 0 bytes in 0 blocks
==6892== still reachable: 117,816 bytes in 14 blocks
==6892== suppressed: 0 bytes in 0 blocks
==6892== Reachable blocks (those to which a pointer was found) are not shown.
==6892== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==6892==
==6892== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
==6892==
==6892== 1 errors in context 1 of 1:
==6892== Invalid read of size 1
==6892== at 0x1308C0: pcre2_match_8 (in pcre-10.34-RC1/pcre2test)
==6892== by 0x111C49: process_data (in pcre-10.34-RC1/pcre2test)
==6892== by 0x115703: main (in pcre-10.34-RC1/pcre2test)
==6892== Address 0x524b550 is 0 bytes after a block of size 16,384 alloc'd
==6892== at 0x4C2FA3F: malloc (in
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6892== by 0x4C31D84: realloc (in
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6892== by 0x110283: process_data (in pcre-10.34-RC1/pcre2test)
==6892== by 0x115703: main (in pcre-10.34-RC1/pcre2test)
==6892==
==6892== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
====================
Crash triage:
--------------------
Function: GETCHARINCTEST(fc, Feptr);
//F->eptr = (PCRE2_SPTR8) 0x6290000041ff <incomplete sequence \314>
//0x6290000041ff: 0xcc 0x00 0x00 0x00 0x00 0x00
GETCHARINCTEST(fc, Feptr){
fc = *F->eptr++; // fc = 204 0xcc, F->eptr =
(PCRE2_SPTR8) 0x629000004200 "", *F->eptr =0x00
if (utf && fc >= 0xc0u) {
if ((fc & 0x20u) == 0) // executes this block
fc = ((fc & 0x1fu) << 6) | (*F->eptr++ & 0x3fu); //Heap
buffer overflow at *F->eptr++
else if ((fc & 0x10u) == 0) {
fc = ((fc & 0x0fu) << 12) | ((*F->eptr & 0x3fu) << 6) | (F->eptr[1]
& 0x3fu);
F->eptr += 2;
} else if ((fc & 0x08u) == 0) {
fc = ((fc & 0x07u) << 18) | ((*F->eptr & 0x3fu) << 12) |
((F->eptr[1] & 0x3fu) << 6) | (F->eptr[2] & 0x3fu);
F->eptr += 3;
} else if ((fc & 0x04u) == 0) {
fc = ((fc & 0x03u) << 24) | ((*F->eptr & 0x3fu) << 18) |
((F->eptr[1] & 0x3fu) << 12) | ((F->eptr[2] & 0x3fu) << 6) | (F->eptr[3] &
0x3fu); F->eptr += 4;
} else {
fc = ((fc & 0x01u) << 30) | ((*F->eptr & 0x3fu) << 24) |
((F->eptr[1] & 0x3fu) << 18) | ((F->eptr[2] & 0x3fu) << 12) | ((F->eptr[3] &
0x3fu) << 6) | (F->eptr[4] & 0x3fu);
F->eptr += 5;
}
}
}
=====================
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