CVE-2025-68329

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.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.