CVE-2025-39754
📋 TL;DR
This CVE describes a race condition vulnerability in the Linux kernel's memory management subsystem where the smaps_hugetlb_range function accesses page table entries without proper locking. This can lead to kernel crashes when concurrent memory migration occurs. Systems running affected Linux kernel versions with huge page support are vulnerable.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially causing data corruption or loss in active processes.
Likely Case
System instability or crash when memory migration operations coincide with smaps operations, resulting in temporary denial of service.
If Mitigated
Minor performance impact from additional locking overhead in memory management operations.
🎯 Exploit Status
Exploitation requires triggering a specific race condition between smaps operations and memory migration, which may be difficult to reliably achieve.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel trees (commits: 09fc018f48871123ad5dbd7b03c956580232ed76, 2a1f3663974162b8f1e098196f557cfc1d160138, 45d19b4b6c2d422771c29b83462d84afcbb33f01, b625883ccbcc2b57808db51d1375b1d7b9bcb3e5)
Vendor Advisory: https://git.kernel.org/stable/c/09fc018f48871123ad5dbd7b03c956580232ed76
Restart Required: Yes
Instructions:
1. Update to a patched kernel version from your distribution's repositories. 2. Rebuild kernel if using custom kernel. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable huge pages
LinuxDisable hugetlb support to prevent the vulnerable code path from being triggered
echo never > /sys/kernel/mm/transparent_hugepage/enabled
echo 0 > /proc/sys/vm/nr_hugepages
🧯 If You Can't Patch
- Monitor system logs for kernel panic or BUG_ON messages related to pfn_swap_entry_to_page
- Restrict user access to /proc/[pid]/smaps files to reduce attack surface
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with patched versions from kernel git repositoryCheck Version:
uname -rVerify Fix Applied:
Verify kernel version after update matches or exceeds patched versions, check that /proc/[pid]/smaps operations don't cause crashes📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- BUG_ON in pfn_swap_entry_to_page
- oops messages in dmesg or /var/log/kern.log
Network Indicators:
- None - this is a local kernel vulnerability
SIEM Query:
source="kernel" AND ("BUG_ON" OR "pfn_swap_entry_to_page" OR "kernel panic")