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_iterator_reset, both
iter.seq.len and iter.seq.size were set to 0. Since they are equal,
the WARN_ON_ONCE condition is triggered.
Move the trace_printk_seq() into the if block that checks to make sure the return value of trace_find_next_entry_inc() is non-NULL in ftrace_dump_one(), ensuring the 'iter.seq' is properly populated before subsequent operations.
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 2.6.28 | 5.4.298 |
| linux / linux_kernel | 5.5 | 5.10.242 |
| linux / linux_kernel | 5.11 | 5.15.191 |
| linux / linux_kernel | 5.16 | 6.1.150 |
| linux / linux_kernel | 6.2 | 6.6.104 |
| linux / linux_kernel | 6.7 | 6.12.45 |
| linux / linux_kernel | 6.13 | 6.16.5 |
| linux / linux_kernel | 6.17-rc1 | 6.17-rc1.x |
| linux / linux_kernel | 6.17-rc2 | 6.17-rc2.x |
| debian / debian_linux | 11.0 | 11.0.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
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