CVE-2023-54171

What it actually does

Unconditional allocation of iter->temp in trace_find_next_entry without corresponding free in tracing_release_pipe when trace_pipe is closed, resulting in a kernel memory leak.

Why it matters to the business

Gradual memory exhaustion on Linux systems that use kernel tracing, increasing operational risk of instability or denial of service in high-traffic or long-lived environments where trace_pipe is accessed repeatedly.

How an attack unfolds

An attacker with local access opens and repeatedly reads from trace_pipe, causing trace_find_next_entry to allocate iter->temp buffers that are never released when the file descriptor is closed, accumulating unreferenced kernel memory until the system is impacted.

How to fix it

Upgrade the Linux kernel to a fixed version such as 6.6.109 or newer, or apply the corresponding Debian package updates (6.12.43-1 for Debian 13, 6.16.3-1 for Debian 14) and reboot.

How to confirm the fix worked

Verify the running kernel version matches or exceeds the listed fixed releases; re-run kmemleak after trace_pipe usage to confirm absence of the previously reported unreferenced iter->temp objects.

Typical attack path

1. Obtain local user access on an affected Linux system
2. Open /sys/kernel/debug/tracing/trace_pipe or equivalent
3. Perform repeated read operations on the pipe
4. Close the file descriptor without triggering the missing free path
5. Repeat to accelerate memory consumption

How to detect it

Review kmemleak output for unreferenced objects allocated via __kmalloc with backtraces containing trace_find_next_entry, trace_print_lat_context, and tracing_read_pipe; correlate with processes that opened trace_pipe.

What your security team should do

• Apply the kernel update to all affected systems within the next maintenance window
• Disable or restrict access to trace_pipe on systems where tracing is not required
• Monitor kmemleak reports for similar allocation patterns in tracing code
• Include kernel version checks in vulnerability scanning and asset inventories