CVE-2025-39813

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

ftrace: Fix potential warning in trace_printk_seq during ftrace_dump

When calling ftrace_dump_one() concurrently with reading trace_pipe,

a WARN_ON_ONCE() in trace_printk_seq() can be triggered due to a race

condition.

The issue occurs because:

CPU0 (ftrace_dump) CPU1 (reader)

echo z > /proc/sysrq-trigger

!trace_empty(&iter)

trace_iterator_reset(&iter) <- len = size = 0

cat /sys/kernel/tracing/trace_pipe

trace_find_next_entry_inc(&iter)

__find_next_entry

ring_buffer_empty_cpu <- all empty

return NULL

trace_printk_seq(&iter.seq)

WARN_ON_ONCE(s->seq.len >= s->seq.size)

In the context between trace_empty() and trace_find_next_entry_inc()

during ftrace_dump, the ring buffer data was consumed by other readers.

This caused trace_find_next_entry_inc to return NULL, failing to populate

`iter.seq`. At this point, due to the prior trace

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References