CVE-2022-49079
📋 TL;DR
This CVE describes a deadlock vulnerability in the Linux kernel's Btrfs filesystem when using zoned storage. The issue occurs when btrfs_can_activate_zone() attempts to acquire the device_list_mutex while it's already held, causing a system hang. This affects Linux systems using Btrfs with zoned storage devices.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
System deadlock leading to complete filesystem unavailability, requiring system reboot and potential data corruption.
Likely Case
System hang during filesystem operations on zoned storage, requiring manual intervention to recover.
If Mitigated
No impact if patched or if Btrfs zoned storage is not used.
🎯 Exploit Status
This is a deadlock condition, not a traditional security exploit. It requires local access and specific filesystem operations to trigger.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in Linux kernel commits: 09e65ae515af2b24d6dc23af21719a3b41de83e5, 0b9e66762aa0cda2a9c2d5542d64e04dac528fa6, 142f822bd945a7be442a2916ec6167cc102c4183
Vendor Advisory: https://git.kernel.org/stable/c/09e65ae515af2b24d6dc23af21719a3b41de83e5
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix. 2. Check with your distribution for backported patches. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable Btrfs zoned mode
linuxAvoid using Btrfs with zoned storage devices until patched.
# Do not format or mount zoned devices with Btrfs
# Use alternative filesystems for zoned storage
Use alternative filesystem
linuxUse ext4, XFS, or other filesystems for zoned storage devices.
mkfs.ext4 /dev/zoned_device
mkfs.xfs /dev/zoned_device
🧯 If You Can't Patch
- Avoid using Btrfs with zoned storage devices
- Implement monitoring for system hangs and have reboot procedures ready
🔍 How to Verify
Check if Vulnerable:
Check if using Btrfs with zoned devices: 'cat /proc/mounts | grep btrfs' and check device types with 'lsblk -o NAME,TYPE,MOUNTPOINT,FSTYPE'Check Version:
uname -rVerify Fix Applied:
Check kernel version contains fix commits: 'uname -r' and verify with distribution patch notes📡 Detection & Monitoring
Log Indicators:
- Kernel logs showing 'possible recursive locking detected'
- System hang messages in dmesg
- Btrfs error messages related to device_list_mutex
Network Indicators:
- None - this is a local filesystem issue
SIEM Query:
source="kernel" AND "possible recursive locking detected" AND "device_list_mutex"