CVE-2023-53187
📋 TL;DR
This is a use-after-free vulnerability in the Linux kernel's Btrfs filesystem that occurs when a newly created block group becomes unused before its creation is fully completed. The vulnerability can lead to kernel crashes (denial of service) and potentially memory corruption. It 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, with potential for memory corruption that could be leveraged for privilege escalation or further system compromise.
Likely Case
System crash/panic during filesystem operations (particularly during unmount or block group management), resulting in denial of service and potential data loss or corruption.
If Mitigated
No impact if patched or if Btrfs is not used; limited to systems with Btrfs filesystems under specific timing conditions.
🎯 Exploit Status
Exploitation requires local access and ability to perform filesystem operations. The vulnerability was discovered through fstests (generic/297).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in Linux kernel stable commits: 0657b20c5a76c938612f8409735a8830d257866e, 6297644db23f77c02ae7961cc542d162629ae2c4, 7569c4294ba6ff9f194635b14876198f8a687c4a
Vendor Advisory: https://git.kernel.org/stable/c/0657b20c5a76c938612f8409735a8830d257866e
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix. 2. Check your distribution's security advisories for specific patched kernel versions. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Avoid Btrfs filesystem
linuxUse alternative filesystems like ext4 or XFS instead of Btrfs
Limit filesystem operations
linuxRestrict user access to Btrfs filesystem operations that could trigger block group creation
🧯 If You Can't Patch
- Monitor system logs for Btrfs-related crashes or assertion failures
- Implement strict access controls to limit who can perform filesystem operations on Btrfs volumes
🔍 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 patched and test with fstests generic/297 if available📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages mentioning Btrfs, block-group.c:4299 assertion failures, 'invalid opcode' errors during unmount
Network Indicators:
- None - this is a local filesystem vulnerability
SIEM Query:
source="kernel" AND ("btrfs" AND ("panic" OR "BUG" OR "assertion failed"))