php / php/php-src

UBSan: Negation of PHP_INT_MIN triggers runtime error in streams/memory.c via SplTempFileObject::fseek

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  • #20922 by @arshidkv12 — closed without merging
Bug Category: Streams Status: Verified
Dominant language
C
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Description

Description

The following code:

<?php
$cls = new SplTempFileObject();
$fusion = $cls;
var_dump($fusion->fseek(PHP_INT_MIN, SEEK_END));

Resulted in this output:

/home/phpfuzz/WorkSpace/flowfusion/php-src/main/streams/memory.c:168:45: runtime error: negation of -9223372036854775808 cannot be represented in type 'zend_off_t' (aka 'long'); cast to an unsigned type to negate this value to itself
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/phpfuzz/WorkSpace/flowfusion/php-src/main/streams/memory.c:168:45 in 

To reproduce:

./php-src/sapi/cli/php  ./test.php

Commit:

9ab800ec9b5959dfe3d4cde50f7a27a763d102f8

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 report is automatically generated by FlowFusion

PHP Version
nightly
Operating System

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start in main/streams/memory.c around line 168 and trace the SplTempFileObject::fseek entry point using the provided PHP_INT_MIN and SEEK_END reproduction in test.php. Run the UBSan command shown in the report; done means this input no longer triggers the negation runtime error.

Written by the indexing model from the issue text.

Assessment

Tech stack
c, php
Domain
backend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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