CVE-2025-38517
📋 TL;DR
A NULL pointer dereference vulnerability in the Linux kernel's memory allocation tagging subsystem causes a kernel crash when attempting to lock a non-existent semaphore. This occurs when memory profiling is disabled or not properly initialized, leading to a system crash that can cause denial of service. All Linux systems with affected kernel versions are potentially 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 →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
Complete system crash and denial of service requiring physical or remote console access to reboot the system.
Likely Case
System crash during memory allocation failures when memory profiling is disabled, causing service disruption.
If Mitigated
No impact if patched or if memory profiling is properly enabled and initialized.
🎯 Exploit Status
Requires ability to trigger memory allocation failures or have memory profiling disabled at boot. Not directly remote exploitable.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in stable kernel releases via commits: 22bf79c0c2301b6e15a688220284b147774d277e, 99af22cd34688cc0d535a1919e0bea4cbc6c1ea1, febc0b5dbabda414565bdfaaaa59d26f787d5fe7
Vendor Advisory: https://git.kernel.org/stable/c/22bf79c0c2301b6e15a688220284b147774d277e
Restart Required: Yes
Instructions:
1. Update to patched kernel version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.
🔧 Temporary Workarounds
Enable memory profiling
allEnsure memory profiling is enabled at boot to avoid the uninitialized state that triggers the vulnerability
Add 'mem_profiling=1' to kernel boot parameters
🧯 If You Can't Patch
- Monitor system logs for memory allocation failures and kernel crashes
- Implement resource limits to reduce likelihood of memory allocation failures
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if memory profiling is disabled: cat /proc/cmdline | grep -q mem_profiling=0 && echo 'Potentially vulnerable if kernel version is affected'Check Version:
uname -rVerify Fix Applied:
Check kernel version is patched: uname -r and verify it's newer than vulnerable versions. Check dmesg for absence of alloc_tag_top_users crash messages.📡 Detection & Monitoring
Log Indicators:
- Kernel panic/Oops messages mentioning alloc_tag_top_users
- General protection fault errors with null-ptr-deref in KASAN range
- System crash logs with call trace including alloc_tag_top_users
Network Indicators:
- None - this is a local kernel vulnerability
SIEM Query:
source="kernel" AND ("alloc_tag_top_users" OR "null-ptr-deref" AND "KASAN")