ext/gd: fix undefined behavior with GIFs with problematic LZW compression data

[DanielEScherzer]

Apply the changes from libgd/libgd@9fa3abd in order to fix undefined behavior from out-of-bounds reads when creating a GIF with problematic LZW compression data.

[DanielEScherzer]

This is only needed for PHP 8.4 and 8.5, 8.6 included the fix as part of #22532

Without this fix, UBSAN_OPTIONS=print_stacktrace=1 /usr/src/php84/sapi/cli/php /var/www/html/gd.php results in

/usr/src/php84/ext/gd/libgd/gd_gif_in.c:520:16: runtime error: index 8191 out of bounds for type 'int[4096]'
    #0 0x565139ecd914 in LWZReadByte_ /usr/src/php84/ext/gd/libgd/gd_gif_in.c:520:16
    #1 0x565139eca615 in LWZReadByte /usr/src/php84/ext/gd/libgd/gd_gif_in.c:554:7
    #2 0x565139ec9f52 in ReadImage /usr/src/php84/ext/gd/libgd/gd_gif_in.c:604:14
    #3 0x565139ec87dd in php_gd_gdImageCreateFromGifCtx /usr/src/php84/ext/gd/libgd/gd_gif_in.c:252:4
    #4 0x565139e55485 in _php_image_create_from_string /usr/src/php84/ext/gd/gd.c:1448:7
    #5 0x565139e54591 in zif_imagecreatefromstring /usr/src/php84/ext/gd/gd.c:1494:9
    #6 0x56513b70635d in ZEND_DO_ICALL_SPEC_RETVAL_USED_HANDLER /usr/src/php84/Zend/zend_vm_execute.h:1351:2
    #7 0x56513b35e20f in execute_ex /usr/src/php84/Zend/zend_vm_execute.h:58697:7
    #8 0x56513b35ef7e in zend_execute /usr/src/php84/Zend/zend_vm_execute.h:64349:2
    #9 0x56513bc567e8 in zend_execute_script /usr/src/php84/Zend/zend.c:1937:3
    #10 0x56513ac3824d in php_execute_script_ex /usr/src/php84/main/main.c:2577:13
    #11 0x56513ac38978 in php_execute_script /usr/src/php84/main/main.c:2617:9
    #12 0x56513bc602a9 in do_cli /usr/src/php84/sapi/cli/php_cli.c:935:5
    #13 0x56513bc5dfc5 in main /usr/src/php84/sapi/cli/php_cli.c:1322:18
    #14 0x7f259e0b6249 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #15 0x7f259e0b6304 in __libc_start_main csu/../csu/libc-start.c:360:3
    #16 0x565139403f30 in _start (/usr/src/php84/sapi/cli/php+0x1a03f30) (BuildId: 19ac90755960f95b5e2d9b45f49a35be7b83f33d)

SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /usr/src/php84/ext/gd/libgd/gd_gif_in.c:520:16 in

[DanielEScherzer]

@vapier as the original author of the fix, I've included your GitHub username in the credits in the NEWS entry:

Fixed undefined behavior with GIFs with problematic LZW compression data.
(DanielEScherzer, vapier)

please let me know if you would like to be credited under a different name

[vapier]

I'm fairly indifferent. thanks for checking.