AddressSanitizer: heap-buffer-overflow in function parse_paragraph at ps-pdf.cxx:5203
hdthky opened this issue · 3 comments
Description
Whilst experimenting with htmldoc, built from commit 0bef12c, we are able to induce a vulnerability at htmldoc/htmldoc/ps-pdf.cxx:5203 in function parse_paragraph , using a harness compiled from htmldoc/htmldoc.cxx.
Because there is no bounds checking, a heap-based out-of-bound read will be triggered when the software encounters a malformed file, result in information disclosure or denial of service.
Environment
Ubuntu 20.04
gcc 10.3.0 with ASAN
Proof of Concept
The POC is: poc_heap_overflow7
The command is: ./htmldoc --webpage -t pdf -f /dev/null poc_heap_overflow7
The ASAN report is:
=================================================================
==9833==ERROR: AddressSanitizer: heap-use-after-free on address 0x6080000005d0 at pc 0x5555555d65cd bp 0x7fffffffa220 sp 0x7fffffffa210
READ of size 4 at 0x6080000005d0 thread T0
#0 0x5555555d65cc in parse_paragraph /work/htmldoc/htmldoc/ps-pdf.cxx:5203
#1 0x5555555f526e in parse_doc /work/htmldoc/htmldoc/ps-pdf.cxx:4572
#2 0x5555555f1976 in parse_doc /work/htmldoc/htmldoc/ps-pdf.cxx:4273
#3 0x5555555f4f23 in parse_doc /work/htmldoc/htmldoc/ps-pdf.cxx:4537
#4 0x555555604d71 in pspdf_export /work/htmldoc/htmldoc/ps-pdf.cxx:803
#5 0x55555559f764 in main /work/htmldoc/htmldoc/htmldoc.cxx:1291
#6 0x7ffff6b620b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
#7 0x55555559fbcd in _start (/work/htmldoc/htmldoc/htmldoc+0x4bbcd)
0x6080000005d0 is located 48 bytes inside of 96-byte region [0x6080000005a0,0x608000000600)
freed by thread T0 here:
#0 0x7ffff769b8f7 in __interceptor_free ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:127
#1 0x5555555d4b91 in parse_paragraph /work/htmldoc/htmldoc/ps-pdf.cxx:4881
previously allocated by thread T0 here:
#0 0x7ffff769be17 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x5555555d0470 in flatten_tree /work/htmldoc/htmldoc/ps-pdf.cxx:9585
SUMMARY: AddressSanitizer: heap-use-after-free /work/htmldoc/htmldoc/ps-pdf.cxx:5203 in parse_paragraph
Shadow bytes around the buggy address:
0x0c107fff8060: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
0x0c107fff8070: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
0x0c107fff8080: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
0x0c107fff8090: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
0x0c107fff80a0: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c107fff80b0: fa fa fa fa fd fd fd fd fd fd[fd]fd fd fd fd fd
0x0c107fff80c0: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
0x0c107fff80d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c107fff80e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c107fff80f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c107fff8100: 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
==9833==ABORTING
Impact
This vulnerability is capable of inducing information disclosure or denial of service.
Denial of service perhaps, information disclosure unlikely.
Maybe I misrepresent it, I just wanted to say it's possible.