CVE-2022-50529
📋 TL;DR
This CVE describes a memory leak vulnerability in the Linux kernel's test_firmware module. When misc_register() fails during module initialization, the kernel fails to free allocated memory for the test_firmware configuration name. This affects systems with the test_firmware module loaded, typically during development or testing scenarios.
💻 Affected Systems
- Linux kernel
⚠️ Risk & Real-World Impact
Worst Case
Sustained memory exhaustion leading to kernel panic or system instability if the vulnerable code path is repeatedly triggered, potentially causing denial of service.
Likely Case
Minor memory leak that accumulates slowly over time, primarily affecting systems where test_firmware module is frequently loaded/unloaded during development or testing.
If Mitigated
No impact on production systems where test_firmware module is not loaded, or minimal impact with proper memory monitoring.
🎯 Exploit Status
Requires ability to load kernel modules (typically root privileges) and trigger the specific failure condition in misc_register().
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple stable kernel versions with fixes available (see references)
Vendor Advisory: https://git.kernel.org/stable/c/04dd47a2e169f2d4489636afa07ff0469aab49ab
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify test_firmware module is not loaded unless needed.
🔧 Temporary Workarounds
Prevent test_firmware module loading
linuxBlacklist the test_firmware module to prevent it from being loaded
echo 'blacklist test_firmware' >> /etc/modprobe.d/blacklist.conf
update-initramfs -u
Unload test_firmware module
linuxRemove the module if currently loaded
rmmod test_firmware
🧯 If You Can't Patch
- Ensure test_firmware module is not loaded in production systems
- Implement kernel module loading restrictions and monitoring
🔍 How to Verify
Check if Vulnerable:
Check if test_firmware module is loaded: lsmod | grep test_firmwareCheck Version:
uname -rVerify Fix Applied:
Check kernel version is patched: uname -r and verify against distribution security advisories📡 Detection & Monitoring
Log Indicators:
- Kernel messages about memory allocation failures
- System logs showing test_firmware module loading
Network Indicators:
- None - this is a local vulnerability
SIEM Query:
source="kernel" AND ("test_firmware" OR "misc_register failed")🔗 References
- https://git.kernel.org/stable/c/04dd47a2e169f2d4489636afa07ff0469aab49ab
- https://git.kernel.org/stable/c/0b5a89e8bce1ea43687742b4de8e216189ff94ac
- https://git.kernel.org/stable/c/357379d504c0c8b0834e206ad8c49e4b3c98ed4d
- https://git.kernel.org/stable/c/628de998a3abfffb3f9677d2fb39a1d5dcb32fdb
- https://git.kernel.org/stable/c/6dd5fbd243f19f087dc79481acb7d69fb57fea2c
- https://git.kernel.org/stable/c/7610615e8cdb3f6f5bbd9d8e7a5d8a63e3cabf2e
- https://git.kernel.org/stable/c/8d8c1d6a430f0aadb80036e2b1bc0a05f9fad247
- https://git.kernel.org/stable/c/ed5cbafaf7ce8b86f19998c00eb020c8d49b017f
