ImageMagick has a Memory Leak in LoadOpenCLDeviceBenchmark() when parsing malformed XML

Summary

### Summary A memory leak vulnerability exists in the `LoadOpenCLDeviceBenchmark()` function in `MagickCore/opencl.c`. When parsing a malformed OpenCL device profile XML file that contains `<device` elements without proper `/>` closing tags, the function fails to release allocated memory for string members (`platform_name`, `vendor_name`, `name`, `version`), leading to memory leaks that could result in resource exhaustion. **Affected Version**: ImageMagick 7.1.2-12 and possibly earlier versions --- ### Details The vulnerability is located in `MagickCore/opencl.c`, function `LoadOpenCLDeviceBenchmark()` (lines 754-911). **Root Cause Analysis:** 1. When a `<device` tag is encountered, a `MagickCLDeviceBenchmark` structure is allocated (line 807-812) 2. String attributes (`platform`, `vendor`, `name`, `version`) are allocated via `ConstantString()` (lines 878, 885, 898, 900) 3. These strings are **only freed** when a `/>` closing tag is encountered (lines 840-849) 4. At function exit (lines 908-910), only the `device_benchmark` structure is freed, but **its member variables are not freed** if `/>` was never parsed **Vulnerable Code (lines 908-910):** ```c token=(char *) RelinquishMagickMemory(token); device_benchmark=(MagickCLDeviceBenchmark *) RelinquishMagickMemory( device_benchmark); // BUG: members (platform_name, vendor_name, name, version) not freed! ``` **Correct cleanup (only executed when `/>` is found, lines 840-849):** ```c device_benchmark->platform_name=(char *) RelinquishMagickMemory(device_benchmark->platform_name); device_benchmark->vendor_name=(char *) RelinquishMagickMemory(device_benchmark->vendor_name); device_benchmark->name=(char *) RelinquishMagickMemory(device_benchmark->name); device_benchmark->version=(char *) RelinquishMagickMemory(device_benchmark->version); device_benchmark=(MagickCLDeviceBenchmark *) RelinquishMagickMemory(device_benchmark); ``` --- ### PoC **Environment:** - OS: Ubuntu 22.04.5 LTS (Linux 6.8.0-87-generic x86_64) - Compiler: GCC 11.4.0 - ImageMagick: 7.1.2-13 (commit `a52c1b402be08ef8ae193f28ac5b2e120f2fa26f`) **Step 1: Build ImageMagick with AddressSanitizer** ```bash cd ImageMagick ./configure \ CFLAGS="-g -O0 -fsanitize=address -fno-omit-frame-pointer" \ CXXFLAGS="-g -O0 -fsanitize=address -fno-omit-frame-pointer" \ LDFLAGS="-fsanitize=address" \ --disable-openmp make -j$(nproc) ``` **Step 2: Create malformed XML file** **Step 3: Place file in OpenCL cache directory** ```bash mkdir -p ~/.cache/ImageMagick cp malformed_opencl_profile.xml ~/.cache/ImageMagick/ImagemagickOpenCLDeviceProfile.xml ``` **Step 4: Run ImageMagick with leak detection** ```bash export ASAN_OPTIONS="detect_leaks=1:symbolize=1" ./utilities/magick -size 100x100 xc:red output.png ``` **ASAN Output:** ``` ================================================================= ==2543490==ERROR: LeakSanitizer: detected memory leaks Direct leak of 96 byte(s) in 2 object(s) allocated from: #0 ... in AcquireMagickMemory MagickCore/memory.c:536 #1 ... in LoadOpenCLDeviceBenchmark MagickCore/opencl.c:807 Direct leak of 16 byte(s) in 1 object(s) allocated from: #0 ... in ConstantString MagickCore/string.c:692 #1 ... in LoadOpenCLDeviceBenchmark MagickCore/opencl.c:878 ← name Direct leak of 14 byte(s) in 1 object(s) allocated from: #0 ... in ConstantString MagickCore/string.c:692 #1 ... in LoadOpenCLDeviceBenchmark MagickCore/opencl.c:885 ← platform_name Direct leak of 14 byte(s) in 1 object(s) allocated from: #0 ... in ConstantString MagickCore/string.c:692 #1 ... in LoadOpenCLDeviceBenchmark MagickCore/opencl.c:898 ← vendor_name Direct leak of 15 byte(s) in 1 object(s) allocated from: #0 ... in ConstantString MagickCore/string.c:692 #1 ... in LoadOpenCLDeviceBenchmark MagickCore/opencl.c:900 ← version SUMMARY: AddressSanitizer: 203 byte(s) leaked in 18 allocation(s). ``` --- ### Impact **Vulnerability Type:** CWE-401 (Missing Release of Memory after Effective Lifetime) **Severity:** Low **Who is impacted:** - Users who have OpenCL enabled in ImageMagick - Systems where an attacker can place or modify files in the OpenCL cache directory (`~/.cache/ImageMagick/`) - Long-running ImageMagick processes or services that repeatedly initialize OpenCL **Potential consequences:** - Memory exhaustion over time if the malformed configuration is repeatedly loaded - Denial of Service (DoS) in resource-constrained environments **Attack Vector:** Local - requires write access to the user's OpenCL cache directory