CVE-2025-68329 tracing: Fix WARN_ON in tracing_buffers_mmap_close for split VMAs
A local attacker can trigger a kernel warning and potential instability by splitting trace buffer VMAs, requiring a kernel patch to prevent invalid partial unmapping.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-68329?
CVE-2025-68329 is a denial of service vulnerability in Linux, published on 22 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix WARN_ON in tracing_buffers_mmap_close for split VMAs
When a VMA is split (e.g., by partial munmap or MAP_FIXED), the kernel calls vm_ops->close on each portion. For trace buffer mappings, this results in ring_buffer_unmap() being called multiple times while ring_buffer_map() was only called once.
This causes ring_buffer_unmap() to return -ENODEV on subsequent calls because user_mapped is already 0, triggering a WARN_ON.
Trace buffer mappings cannot support partial mappings because the ring buffer structure requires the complete buffer including the meta page.
Fix this by adding a may_split callback that returns -EINVAL to prevent VMA splits entirely.
Which versions are affected by CVE-2025-68329?
How do I fix CVE-2025-68329?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-68329 being exploited?
There is no known exploitation of CVE-2025-68329 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-68329, DEBIAN-CVE-2025-68329, GHSA-6jcw-grc8-h79f, UBUNTU-CVE-2025-68329.