CVE-2022-41850: Linux Kernel Use-After-Free Vulnerability

CVE-2022-41850 Overview

A race condition vulnerability exists in the roccat_report_event function within drivers/hid/hid-roccat.c in the Linux kernel through version 5.19.12. This flaw results in a use-after-free condition that occurs when a report is received while copying a report->value is still in progress. The vulnerability is classified as CWE-362 (Race Condition).

Critical Impact

Successful exploitation of this race condition can lead to a denial of service condition, causing system instability or crashes on affected Linux systems.

Affected Products

• Linux Kernel (through version 5.19.12)
• Debian Linux 10.0

Discovery Timeline

• 2022-09-30 - CVE-2022-41850 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-41850

Vulnerability Analysis

This vulnerability affects the HID (Human Interface Device) subsystem of the Linux kernel, specifically the Roccat device driver. The flaw exists in the roccat_report_event function, which handles incoming reports from Roccat gaming peripherals. The race condition occurs during concurrent access to report data structures, where one execution context may free memory that another context is actively reading from or writing to.

The vulnerability requires local access to exploit, as an attacker would need to interact with the Roccat HID driver on the target system. While the attack complexity is high due to the timing-dependent nature of race conditions, successful exploitation does not require user interaction. The primary impact is on system availability, potentially causing kernel panics or system crashes.

Root Cause

The root cause is a classic Time-of-Check Time-of-Use (TOCTOU) race condition in the roccat_report_event function. When the driver receives a HID report, it copies the report value without proper synchronization primitives. If another report arrives or the underlying data structure is modified during this copy operation, the memory being accessed may be freed by a concurrent execution path, resulting in a use-after-free condition.

The lack of adequate locking mechanisms around the report value copy operation allows concurrent threads to access and potentially free the same memory region simultaneously.

Attack Vector

The attack vector is local, requiring an attacker to have low-privileged access to a system with the vulnerable Roccat HID driver loaded. The exploitation scenario involves:

1. The attacker connects a Roccat HID device (or emulates one) to the target system
2. By manipulating the timing of HID report submissions, the attacker triggers the race condition
3. When successful, the use-after-free occurs during the report->value copy operation
4. This leads to kernel memory corruption and potential denial of service

Due to the high attack complexity and timing-sensitive nature of race conditions, reliable exploitation is challenging but not impossible for a determined attacker with physical or privileged access.

Detection Methods for CVE-2022-41850

Indicators of Compromise

• Unexpected kernel panics or oops messages referencing hid-roccat.c or roccat_report_event
• System crashes occurring when Roccat HID devices are connected or in use
• Kernel log entries showing use-after-free detection by KASAN (Kernel Address Sanitizer) in the HID subsystem

Detection Strategies

• Enable KASAN (Kernel Address Sanitizer) to detect use-after-free conditions at runtime
• Monitor kernel logs for HID-related error messages and crashes
• Implement kernel module auditing to track loading of the hid-roccat driver
• Deploy endpoint detection solutions that monitor for anomalous kernel behavior

Monitoring Recommendations

• Review dmesg and /var/log/kern.log for recurring HID driver errors
• Set up alerts for kernel panic events on systems with Roccat devices
• Monitor for unauthorized HID device connections that could indicate exploitation attempts
• Implement SentinelOne's kernel-level monitoring for real-time detection of memory corruption attacks

How to Mitigate CVE-2022-41850

Immediate Actions Required

• Update the Linux kernel to a patched version that includes commit cacdb14b1c8d3804a3a7d31773bc7569837b71a4
• For Debian Linux 10.0 users, apply security updates from the Debian LTS announcements
• If updates cannot be immediately applied, consider blacklisting the hid-roccat module if Roccat devices are not required
• Review system logs for any evidence of prior exploitation attempts

Patch Information

The vulnerability has been addressed through a kernel commit that adds proper synchronization to the roccat_report_event function. The fix ensures that report data is not accessed after being freed by implementing appropriate locking mechanisms.

The patch is available in the Linux kernel git repository: Linux Kernel Commit Update

Debian users should refer to the Debian LTS Security Advisory for distribution-specific patching guidance.

Workarounds

• Blacklist the hid-roccat kernel module using modprobe.d configuration if Roccat devices are not needed
• Restrict physical access to USB ports to prevent malicious HID device connections
• Use USB device whitelisting to allow only authorized HID devices
• Consider implementing usbguard for granular USB device access control

# Blacklist the hid-roccat module if not needed
echo "blacklist hid-roccat" | sudo tee /etc/modprobe.d/blacklist-roccat.conf
sudo update-initramfs -u