CVE-2024-57942
📋 TL;DR
A race condition in the Linux kernel's netfs subsystem causes a hang when writing to Ceph filesystems with fsc (filesystem caching) enabled. This affects Linux systems using Ceph storage with cachefilesd enabled, potentially causing denial of service during write operations.
💻 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 →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 hangs during write operations to Ceph filesystems, requiring reboot to restore functionality.
Likely Case
Intermittent hangs during file writes to Ceph storage, causing application timeouts and degraded performance.
If Mitigated
No impact if Ceph fsc feature is disabled or cachefilesd is not running.
🎯 Exploit Status
Requires ability to write to Ceph filesystem with specific configuration. More of a reliability bug than security vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel commits 38cf8e945721ffe708fa675507465da7f4f2a9f7 and 43b8d3249b0b71bad239d42dbe08ce6c938ba000
Vendor Advisory: https://git.kernel.org/stable/c/38cf8e945721ffe708fa675507465da7f4f2a9f7
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 Ceph fsc caching
linuxMount Ceph filesystem without the fsc option to avoid the vulnerable code path
mount -t ceph <server>:/ <mountpoint> -o name=<user>,secret=<key>
Stop cachefilesd service
linuxDisable the cachefiles daemon to prevent cache operations
systemctl stop cachefilesd
systemctl disable cachefilesd
🧯 If You Can't Patch
- Monitor systems for hangs during Ceph write operations and have reboot procedures ready
- Implement application-level retry logic for file operations to Ceph storage
🔍 How to Verify
Check if Vulnerable:
Check if Ceph is mounted with fsc: 'mount | grep ceph | grep fsc' and if cachefilesd is running: 'systemctl status cachefilesd'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 hangs or stalls in dmesg
- Application timeouts when writing to Ceph filesystems
- Cachefilesd service errors
Network Indicators:
- Increased latency to Ceph storage cluster
- Timeout errors from applications using Ceph
SIEM Query:
source="kernel" AND ("hang" OR "stall") AND "ceph" OR source="cachefilesd" AND error