CVE-2024-42250
📋 TL;DR
This CVE describes a race condition vulnerability in the Linux kernel's cachefiles subsystem where the poll routine lacks proper spinlock protection when iterating through xarray structures. This could allow an attacker to cause use-after-free conditions or kernel crashes. It affects Linux systems using the cachefiles module.
💻 Affected Systems
- Linux kernel
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially allowing local privilege escalation if combined with other vulnerabilities.
Likely Case
System instability, kernel crashes, or denial of service affecting the cachefiles functionality.
If Mitigated
Minimal impact if cachefiles module is not in use or proper kernel hardening is implemented.
🎯 Exploit Status
Requires local access and ability to trigger cachefiles operations. Race conditions can be challenging to exploit reliably.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits: 6bb6bd3dd6f382dfd36220d4b210a0c77c066651, 8eadcab7f3dd809edbe5ae20533ff843dfea3a07, 97cfd5e20ddc2e33e16ce369626ce76c9a475fd7, cf5bb09e742a9cf6349127e868329a8f69b7a014
Vendor Advisory: https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.
🔧 Temporary Workarounds
Disable cachefiles module
linuxUnload the cachefiles kernel module if not required
sudo modprobe -r cachefiles
echo 'blacklist cachefiles' | sudo tee /etc/modprobe.d/blacklist-cachefiles.conf
🧯 If You Can't Patch
- Ensure cachefiles module is not loaded (check with 'lsmod | grep cachefiles')
- Implement strict access controls to limit local user privileges
🔍 How to Verify
Check if Vulnerable:
Check if cachefiles module is loaded: 'lsmod | grep cachefiles'. If loaded, check kernel version against patched versions.Check Version:
uname -rVerify Fix Applied:
Verify kernel version after update matches patched version, confirm cachefiles module loads without issues.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/kern.log or dmesg
- Cachefiles-related errors or crashes
Network Indicators:
- None - this is a local kernel vulnerability
SIEM Query:
Search for kernel panic events or cachefiles module crashes in system logs🔗 References
- https://git.kernel.org/stable/c/6bb6bd3dd6f382dfd36220d4b210a0c77c066651
- https://git.kernel.org/stable/c/8eadcab7f3dd809edbe5ae20533ff843dfea3a07
- https://git.kernel.org/stable/c/97cfd5e20ddc2e33e16ce369626ce76c9a475fd7
- https://git.kernel.org/stable/c/cf5bb09e742a9cf6349127e868329a8f69b7a014
- https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html
