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Date: Thu, 2 Mar 2017 16:34:57 +0000
From: "Agostino Sarubbo" <ago@...too.org>
To: "oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>
Subject: podofo: heap-based buffer overflow in PoDoFo::PdfVariant::DelayedLoad (PdfVariant.h)

Description:
podofo is a C++ library to work with the PDF file format.

A fuzz on it discovered an heap overflow. The upstream project denies me to open a new ticket. So, I just will forward this on the -users mailing list.

The complete ASan output:

# podofocolor dummy $FILE foo
==5749==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x62500000a0f8 at pc 0x000000529e84 bp 0x7ffee90e1ad0 sp 0x7ffee90e1ac8
READ of size 1 at 0x62500000a0f8 thread T0
    #0 0x529e83 in PoDoFo::PdfVariant::DelayedLoad() const /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/podofo/base/../../src/base/PdfVariant.h:545:10
    #1 0x529e83 in PoDoFo::PdfVariant::GetReal() const /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/podofo/base/../../src/base/PdfVariant.h:675
    #2 0x52887e in ColorChanger::GetColorFromStack(int, std::vector<PoDoFo::PdfVariant, std::allocator >&) /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/tools/podofocolor/colorchanger.cpp:423:33
    #3 0x525d4b in ColorChanger::ProcessColor(ColorChanger::EKeywordType, int, std::vector<PoDoFo::PdfVariant, std::allocator >&, GraphicsStack&) /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/tools/podofocolor/colorchanger.cpp:449:28
    #4 0x521b3c in ColorChanger::ReplaceColorsInPage(PoDoFo::PdfCanvas*) /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/tools/podofocolor/colorchanger.cpp:214:31
    #5 0x51ed8e in ColorChanger::start() /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/tools/podofocolor/colorchanger.cpp:120:15
    #6 0x51c06d in main /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/tools/podofocolor/podofocolor.cpp:116:12
    #7 0x7f6c2623561f in __libc_start_main /var/tmp/portage/sys-libs/glibc-2.22-r4/work/glibc-2.22/csu/libc-start.c:289
    #8 0x428718 in _start (/usr/bin/podofocolor+0x428718)

0x62500000a0f8 is located 8 bytes to the left of 8192-byte region [0x62500000a100,0x62500000c100)
allocated by thread T0 here:
    #0 0x518700 in operator new(unsigned long) /tmp/portage/sys-devel/llvm-3.9.0-r1/work/llvm-3.9.0.src/projects/compiler-rt/lib/asan/asan_new_delete.cc:78
    #1 0x52aa18 in __gnu_cxx::new_allocator::allocate(unsigned long, void const*) /usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/include/g++-v4/ext/new_allocator.h:104:27
    #2 0x52aa18 in __gnu_cxx::__alloc_traits<std::allocator >::allocate(std::allocator&, unsigned long) /usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/include/g++-v4/ext/alloc_traits.h:182
    #3 0x52aa18 in std::_Vector_base<PoDoFo::PdfVariant, std::allocator >::_M_allocate(unsigned long) /usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/include/g++-v4/bits/stl_vector.h:170
    #4 0x52aa18 in std::vector<PoDoFo::PdfVariant, std::allocator >::_M_insert_aux(__gnu_cxx::__normal_iterator<PoDoFo::PdfVariant*, std::vector<PoDoFo::PdfVariant, std::allocator > >, PoDoFo::PdfVariant const&) /usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/include/g++-v4/bits/vector.tcc:353
    #5 0x521bdd in std::vector<PoDoFo::PdfVariant, std::allocator >::push_back(PoDoFo::PdfVariant const&) /usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/include/g++-v4/bits/stl_vector.h:925:4
    #6 0x521bdd in ColorChanger::ReplaceColorsInPage(PoDoFo::PdfCanvas*) /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/tools/podofocolor/colorchanger.cpp:170
    #7 0x51ed8e in ColorChanger::start() /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/tools/podofocolor/colorchanger.cpp:120:15
    #8 0x51c06d in main /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/tools/podofocolor/podofocolor.cpp:116:12
    #9 0x7f6c2623561f in __libc_start_main /var/tmp/portage/sys-libs/glibc-2.22-r4/work/glibc-2.22/csu/libc-start.c:289

SUMMARY: AddressSanitizer: heap-buffer-overflow /tmp/portage/app-text/podofo-0.9.4/work/podofo-0.9.4/podofo/base/../../src/base/PdfVariant.h:545:10 in PoDoFo::PdfVariant::DelayedLoad() const
Shadow bytes around the buggy address:
  0x0c4a7fff93c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c4a7fff93d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c4a7fff93e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c4a7fff93f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c4a7fff9400: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c4a7fff9410: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa[fa]
  0x0c4a7fff9420: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c4a7fff9430: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c4a7fff9440: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c4a7fff9450: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c4a7fff9460: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==5749==ABORTING

Affected version:
0.9.4

Fixed version:
N/A

Commit fix:
N/A

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

CVE:
N/A

Reproducer:
https://github.com/asarubbo/poc/blob/master/00170-podofo-heapoverflow-PoDoFo-PdfTokenizer-GetNextToken

Timeline:
2017-02-13: bug discovered
2017-03-02: bug reported to upstream
2017-03-02: blog post about the issue

Note:
This bug was found with American Fuzzy Lop.

Permalink:
https://blogs.gentoo.org/ago/2017/03/02/podofo-heap-based-buffer-overflow-in-podofopdfvariantdelayedload-pdfvariant-h

--
Agostino Sarubbo
Gentoo Linux Developer


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