Heap overflow when dealing with QT icns image

reproduce steps:

1. compile qt from dev repo with address sanitizer enabled
2. compile image.zip
3. run with poc: ./imageharness ./poc

observed behavior:

```

height: 12, width: 16
=================================================================
==3846283==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x604000000bc0 at pc 0x5615f7a70510 bp 0x7fff291a6e90 sp 0x7fff291a6e80
READ of size 4 at 0x604000000bc0 thread T0
#0 0x5615f7a7050f in main ../../fuzzsrc/image/main.cpp:30
#1 0x7ff0c8252082 in __libc_start_main ../csu/libc-start.c:308
#2 0x5615f7a7097d in _start (/home/casper/targets/bigproj/qt/devtest/fuzzrun/imageharnessafl+0x397d)

0x604000000bc0 is located 0 bytes to the right of 48-byte region [0x604000000b90,0x604000000bc0)
allocated by thread T0 here:
#0 0x7ff0c95e2808 in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cc:144
#1 0x7ff0c8e93285 in QImageData::create(QSize const&, QImage::Format) (/home/casper/targets/bigproj/qt/devtest/INSTALL/lib/libQt6Gui.so.6+0x145285)

SUMMARY: AddressSanitizer: heap-buffer-overflow ../../fuzzsrc/image/main.cpp:30 in main
Shadow bytes around the buggy address:
0x0c087fff8120: fa fa fd fd fd fd fd fa fa fa 00 00 00 00 02 fa
0x0c087fff8130: fa fa fd fd fd fd fd fd fa fa 00 00 00 00 02 fa
0x0c087fff8140: fa fa 00 00 00 00 02 fa fa fa fd fd fd fd fd fa
0x0c087fff8150: fa fa fd fd fd fd fd fa fa fa 00 00 00 00 00 00
0x0c087fff8160: fa fa 00 00 00 00 02 fa fa fa fd fd fd fd fd fa
=>0x0c087fff8170: fa fa 00 00 00 00 00 00[fa]fa fa fa fa fa fa fa
0x0c087fff8180: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff8190: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff81a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff81b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff81c0: 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
==3846283==ABORTING

```