CVE-2024-42228: Linux Kernel Uninitialized Value Flaw

CVE-2024-42228 Overview

CVE-2024-42228 is an uninitialized memory use vulnerability in the Linux kernel's AMD GPU (amdgpu) driver, specifically affecting the Video Compression Engine (VCE) command submission path. The vulnerability occurs when the amdgpu_vce_cs_reloc function is called with an uninitialized *size value in certain code paths, such as case 0x03000001. This uninitialized memory use vulnerability (CWE-908) can potentially lead to information disclosure, privilege escalation, or system instability depending on the memory contents.

Critical Impact

Local attackers with low privileges can potentially exploit uninitialized memory in the amdgpu VCE driver to achieve high impact on confidentiality, integrity, and availability of affected Linux systems with AMD GPUs.

Affected Products

• Linux Kernel (multiple versions with amdgpu driver)
• Systems with AMD GPUs utilizing the VCE subsystem
• Debian-based distributions (see LTS announcements)

Discovery Timeline

• 2024-07-30 - CVE CVE-2024-42228 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2024-42228

Vulnerability Analysis

This vulnerability resides in the amdgpu driver's Video Compression Engine (VCE) command submission handling code. The core issue is that the size variable is not properly initialized before being passed to the amdgpu_vce_cs_reloc function in specific execution paths. When the function processes certain command types (such as case 0x03000001), it may read from this uninitialized memory location, leading to undefined behavior.

The attack requires local access to the system and low privileges, though exploitation complexity is high due to the need to control or predict the uninitialized memory contents. Successful exploitation could allow an attacker to leak sensitive kernel memory information, corrupt kernel data structures, or cause system crashes.

The fix involves initializing the size variable before it is used. As noted in the V2 revision of the patch, the handling was improved by using a separate sentinel value of 0xffffffff to properly track the initialization state.

Root Cause

The root cause is a missing initialization of the size variable in the amdgpu_vce_cs_reloc code path. When certain VCE command submission cases are processed, the function expects a valid size value but receives an uninitialized pointer instead. This is a classic CWE-908 (Use of Uninitialized Resource) vulnerability where the programmer failed to ensure the variable was set to a known value before use.

Attack Vector

The attack vector is local, requiring an attacker to have user-level access to a system with an AMD GPU. The attacker would need to interact with the amdgpu driver through the DRM (Direct Rendering Manager) subsystem, potentially by crafting malicious GPU command submissions that trigger the vulnerable code path. The high attack complexity stems from the requirement to either control the uninitialized memory contents or time the exploitation to coincide with predictable memory states.

The vulnerability can be triggered through userspace GPU applications that submit VCE commands to the kernel driver. An attacker could craft specific command sequences that exercise the uninitialized code path, potentially leading to memory disclosure or corruption.

Detection Methods for CVE-2024-42228

Indicators of Compromise

• Unexpected kernel panics or system crashes related to the amdgpu or VCE subsystems
• Unusual DRM ioctl activity from non-standard processes
• Kernel log messages indicating amdgpu VCE errors or memory corruption
• Abnormal GPU command submission patterns from userspace applications

Detection Strategies

• Monitor kernel logs for amdgpu driver errors, particularly those mentioning VCE or amdgpu_vce_cs_reloc
• Deploy kernel memory sanitizers (KASAN/KMSAN) in testing environments to detect uninitialized memory access
• Use SentinelOne Singularity Platform for real-time kernel-level threat monitoring
• Implement system call auditing for DRM-related ioctls on systems with AMD GPUs

Monitoring Recommendations

• Enable kernel auditing for GPU driver interactions on critical systems
• Monitor for unusual processes accessing /dev/dri/* device nodes
• Configure alerts for kernel oops or panics in the amdgpu driver subsystem
• Regularly review security advisories from Linux kernel maintainers and Debian LTS announcements

How to Mitigate CVE-2024-42228

Immediate Actions Required

• Update the Linux kernel to a patched version containing the fix
• Review the official kernel commits for applicable patches (see patch information below)
• For Debian-based systems, apply updates from the Debian LTS Announcement October 2024 or Debian LTS Announcement January 2025
• Consider restricting access to GPU devices for untrusted users until patching is complete

Patch Information

Multiple patches have been released to address this vulnerability across different kernel versions. The fix initializes the size variable before calling amdgpu_vce_cs_reloc and implements improved handling using a sentinel value of 0xffffffff.

Key patch commits include:

• Linux Kernel Commit 855ae72
• Linux Kernel Commit 88a9a46
• Linux Kernel Commit f8f120b
• Linux Kernel Commit 3b50575
• Linux Kernel Commit 9ee1534

Workarounds

• Restrict access to GPU devices by modifying permissions on /dev/dri/* nodes
• Disable the amdgpu VCE module if video encoding functionality is not required
• Limit unprivileged user access to systems with AMD GPUs until patches are applied
• Deploy runtime kernel exploit detection tools to monitor for exploitation attempts

# Restrict GPU device access to trusted users only
chmod 660 /dev/dri/card*
chown root:video /dev/dri/card*

# Verify current kernel version
uname -r

# Check for available kernel updates (Debian/Ubuntu)
apt update && apt list --upgradable | grep linux