podofo: NULL pointer dereference in PoDoFo::PdfXObject::PdfXObject (PdfXObject.cpp)

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

A fuzz on it discovered a null pointer dereference. 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
==21036==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7fc5cfd94743 bp 0x7ffc1eaffe50 sp 0x7ffc1eaffd40 T0)
==21036==The signal is caused by a READ memory access.
==21036==Hint: address points to the zero page.
    #0 0x7fc5cfd94742 in PoDoFo::PdfXObject::PdfXObject(PoDoFo::PdfObject*) /tmp/portage/app-text/podofo-0.9.5/work/podofo-0.9.5/src/doc/PdfXObject.cpp:264:74
    #1 0x529308 in ColorChanger::start() /tmp/portage/app-text/podofo-0.9.5/work/podofo-0.9.5/tools/podofocolor/colorchanger.cpp:137:28
    #2 0x523b8d in main /tmp/portage/app-text/podofo-0.9.5/work/podofo-0.9.5/tools/podofocolor/podofocolor.cpp:116:12
    #3 0x7fc5cd8d178f in __libc_start_main /tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
    #4 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/src/doc/PdfXObject.cpp:264:74 in PoDoFo::PdfXObject::PdfXObject(PoDoFo::PdfObject*)
==21036==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-2017-6848

Reproducer:
https://github.com/asarubbo/poc/blob/master/00214-podofo-nullptr-PdfXObject-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.

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podofo: NULL pointer dereference in PoDoFo::PdfXObject::PdfXObject (PdfXObject.cpp)

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