integer overflow in imagepng
Open
Nobody has claimed this yet.
Bug
Extension: gd
Status: Verified
- Dominant language
- C
- Stars
- 40.4k
- Forks
- 8.1k
- Avg merge
- 2d 13h
- Merged PRs (30d)
- 96
Description
Description
The following code:
<?php
try {
$exp = imagecreate(100, 100);
imageresolution($exp, 71, 0x80000000);
imagepng($exp, $filename);
} catch (\Throwable $_ffl_e) {}
Resulted in this output:
/home/fuzz/WorkSpace/fusion-fuzz/projects/php/php-src/ext/gd/libgd/gd_png.c:556:54: runtime error: 8.45466e+10 is outside the range of representable values of type 'unsigned int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/fuzz/WorkSpace/fusion-fuzz/projects/php/php-src/ext/gd/libgd/gd_png.c:556:54 in
To reproduce:
./php-src/sapi/cli/php ./test.php
Commit:
dc807bca6d2ea6463748b7398f7910841f96b7ea
Configurations:
CC="clang-12" CXX="clang++-12" CFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" CXXFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" ./configure --enable-debug --enable-address-sanitizer --enable-undefined-sanitizer --enable-re2c-cgoto --enable-fpm --enable-litespeed --enable-phpdbg-debug --enable-zts --enable-bcmath --enable-calendar --enable-dba --enable-dl-test --enable-exif --enable-ftp --enable-gd --enable-gd-jis-conv --enable-mbstring --enable-pcntl --enable-shmop --enable-soap --enable-sockets --enable-sysvmsg --enable-zend-test --with-zlib --with-bz2 --with-curl --with-enchant --with-gettext --with-gmp --with-mhash --with-ldap --with-libedit --with-readline --with-snmp --with-sodium --with-xsl --with-zip --with-mysqli --with-pdo-mysql --with-pdo-pgsql --with-pgsql --with-sqlite3 --with-pdo-sqlite --with-webp --with-jpeg --with-freetype --enable-sigchild --with-readline --with-pcre-jit --with-iconv
Operating System:
Ubuntu 20.04 Host, Docker 0599jiangyc/flowfusion:latest
This bug was found by fusion-fuzz
PHP Version
nightly
Operating System
No response
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start at ext/gd/libgd/gd_png.c around line 556 and reproduce the report with the supplied PHP script under the shown UBSan configuration. Trace how imageresolution values reach imagepng; done means the reproducer no longer reports the integer-conversion undefined behavior, with regression coverage for the case.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c, php
- Domain
- computer-graphics
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 52/100