SEGV on cmft::imageIsCubeCross

[strongcourage]

Hi,

Our fuzzer found a crash due to a SEGV on unknown address bug on the function cmft::imageIsCubeCross. I built cmft (the latest commit 06a3516 on master) using the configuration "release64" on Ubuntu 16.04 (64-bit).

PoC: https://github.com/strongcourage/PoCs/blob/master/cmft_06a3516/PoC_sua_cmft::imageIsCubeCross

ASAN says:

cmftRelease-asan --input $PoC --output0 /dev/null
ASAN:SIGSEGV
=================================================================
==32113==ERROR: AddressSanitizer: SEGV on unknown address 0x7f98bb46a880 (pc 0x000000416918 bp 0x0fffb21b3ede sp 0x7ffd90d9f6d0 T0)
    #0 0x416917 in cmft::imageIsCubeCross(cmft::Image const&, bool) ../../src/cmft/image.cpp:2972
    #1 0x475ae2 in cmftMain(int, char const* const*) ../../src/cmft_cli/cmft_cli.h:938
    #2 0x7f97b996382f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #3 0x403608 in _start (/home/dungnguyen/PoCs/cmft_06a3516/cmftRelease-asan+0x403608)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV ../../src/cmft/image.cpp:2972 cmft::imageIsCubeCross(cmft::Image const&, bool)
==32113==ABORTING

Thanks,
Manh Dung