CVE-2024-56706
📋 TL;DR
A race condition vulnerability in the Linux kernel's s390/cpum_sf component allows concurrent memory allocation of Sample Data Blocks (SDBs) for Performance Monitoring Units (PMUs). This can lead to memory corruption or system instability when multiple perf_event_init() calls run in parallel. Affects Linux systems with s390 architecture using CPU Measurement Facility.
💻 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 or system crash due to memory corruption, potentially causing denial of service on affected s390 systems.
Likely Case
System instability, performance monitoring failures, or kernel crashes when multiple PMU events are created concurrently.
If Mitigated
Minor performance impact from proper mutex locking during PMU initialization.
🎯 Exploit Status
Requires local access and ability to create concurrent PMU events. Race condition exploitation can be timing-sensitive.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel trees via git commits 4b3bdfa89635db6a53e02955548bd07bebcae233 and f55bd479d8663a4a4e403b3d308d3d1aa33d92df
Vendor Advisory: https://git.kernel.org/stable/c/4b3bdfa89635db6a53e02955548bd07bebcae233
Restart Required: Yes
Instructions:
1. Update to patched kernel version from your distribution vendor. 2. For custom kernels, apply git commits 4b3bdfa89635db6a53e02955548bd07bebcae233 and f55bd479d8663a4a4e403b3d308d3d1aa33d92df. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable CPU Measurement Facility
linuxDisable the vulnerable CPUMF component if not required
echo 0 > /sys/kernel/debug/s390_hypfs/cpumf/enable
🧯 If You Can't Patch
- Restrict local user access to systems with s390 architecture
- Monitor for kernel panic/crash events and restrict PMU usage
🔍 How to Verify
Check if Vulnerable:
Check kernel version and architecture: uname -a | grep s390 && check if kernel includes the vulnerable cpum_sf codeCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits or check with distribution vendor for patched kernel version📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- PMU allocation failures in kernel logs
- System crash/reboot events
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("panic" OR "oops" OR "cpum_sf" OR "PMU")