podofo: invalid memory read in ColorChanger::GetColorFromStack (colorchanger.cpp)

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

A fuzz on it discovered an invalid memory read. 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
==9073==ERROR: AddressSanitizer: SEGV on unknown address 0xffffffffffffffe0 (pc 0x000000537d67 bp 0x7ffc54cb3c50 sp 0x7ffc54cb3ba0 T0)
==9073==The signal is caused by a READ memory access.
    #0 0x537d66 in ColorChanger::GetColorFromStack(int, std::vector<PoDoFo::PdfVariant, std::allocator >&) /tmp/portage/app-text/podofo-0.9.5/work/podofo-0.9.5/tools/podofocolor/colorchanger.cpp:416:32
    #1 0x530d50 in ColorChanger::ProcessColor(ColorChanger::EKeywordType, int, std::vector<PoDoFo::PdfVariant, std::allocator >&, GraphicsStack&) /tmp/portage/app-text/podofo-0.9.5/work/podofo-0.9.5/tools/podofocolor/colorchanger.cpp:449:28
    #2 0x52c2a9 in ColorChanger::ReplaceColorsInPage(PoDoFo::PdfCanvas*) /tmp/portage/app-text/podofo-0.9.5/work/podofo-0.9.5/tools/podofocolor/colorchanger.cpp:214:31
    #3 0x526921 in ColorChanger::start() /tmp/portage/app-text/podofo-0.9.5/work/podofo-0.9.5/tools/podofocolor/colorchanger.cpp:120:15
    #4 0x523b8d in main /tmp/portage/app-text/podofo-0.9.5/work/podofo-0.9.5/tools/podofocolor/podofocolor.cpp:116:12
    #5 0x7f36fe7fe78f in __libc_start_main /tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
    #6 0x4300e8 in _start (/usr/bin/podofocolor+0x4300e8)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /tmp/portage/app-text/podofo-0.9.5/work/podofo-0.9.5/tools/podofocolor/colorchanger.cpp:416:32 in ColorChanger::GetColorFromStack(int, std::vector<PoDoFo::PdfVariant, std::allocator >&)
==9073==ABORTING

Affected version:
0.9.5

Fixed version:
N/A

Commit fix:
N/A

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

CVE:
CVE-2017-6840

Reproducer:
https://github.com/asarubbo/poc/blob/master/00215-podofo-invalidread-colorchanger-cpp

Timeline:
2017-03-01: bug discovered
2017-03-02: bug reported upstream
2017-03-02: blog post about the issue
2017-03-12: CVE assigned

Note:
This bug was found with American Fuzzy Lop.

Permalink:

podofo: invalid memory read in ColorChanger::GetColorFromStack (colorchanger.cpp)

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