CVE-2022-49761
📋 TL;DR
This is a use-after-free vulnerability in the Linux kernel's Btrfs filesystem implementation. When run_one_delayed_ref() fails, it can trigger a use-after-free condition that could lead to kernel memory corruption. This affects Linux systems using Btrfs filesystems.
💻 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 →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 →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 →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 →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, system crash, or potential privilege escalation leading to full system compromise.
Likely Case
System instability, kernel crashes, or denial of service affecting Btrfs operations.
If Mitigated
Limited impact if systems don't use Btrfs or have proper kernel hardening.
🎯 Exploit Status
Requires local access and ability to trigger Btrfs delayed ref operations. No known public exploits.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits: 18bd1c9c02e64a3567f90c83c2c8b855531c8098, 39f501d68ec1ed5cd5c66ac6ec2a7131c517bb92, 853ffa1511b058c79a4c9bb1407b3b20ce311792, fdb4a70bb768d2a87890409597529ad81cb3de8a
Vendor Advisory: https://git.kernel.org/stable/c/
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Check distribution-specific security advisories. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Avoid Btrfs usage
linuxUse alternative filesystems like ext4 or xfs instead of Btrfs
Restrict user access
linuxLimit user permissions to reduce ability to trigger Btrfs operations
# Review and tighten file permissions
# Implement least privilege access controls
🧯 If You Can't Patch
- Monitor system logs for Btrfs error messages and kernel crashes
- Implement strict access controls to limit who can perform filesystem operations
🔍 How to Verify
Check if Vulnerable:
Check kernel version and verify if Btrfs is in use: 'uname -r' and 'mount | grep btrfs'Check Version:
uname -rVerify Fix Applied:
Verify kernel version is updated and check for Btrfs error messages in dmesg: 'dmesg | grep -i btrfs'📡 Detection & Monitoring
Log Indicators:
- Btrfs error messages in kernel logs
- Kernel panic or oops messages
- System crashes during filesystem operations
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("btrfs" AND "error") OR ("panic" OR "oops")