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

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):

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):

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

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

mkdir -p ~/.cache/ImageMagick
cp malformed_opencl_profile.xml ~/.cache/ImageMagick/ImagemagickOpenCLDeviceProfile.xml

Step 4: Run ImageMagick with leak detection

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