CVE-2026-89747

Status: UPDATED  |  Advisory ID: CVE-2026-89747

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

tracing: Fix use-after-free in trace_pipe read on sub-buffer order change

Writing to buffer_subbuf_size_kb calls ring_buffer_subbuf_order_set(),

which frees every sub-buffer of the ring buffer, including the reader

page, and replaces them with newly allocated ones.

Readers of trace_pipe hold pointers into those pages. ring_buffer_peek()

looks up an event under cpu_buffer->reader_lock but returns the event

pointer after dropping the lock, and peek_next_entry() then calls

ring_buffer_event_length() and ring_buffer_event_data() on it. If the

sub-buffer order is changed in that window, the reader dereferences

freed memory:

BUG: KASAN: use-after-free in ring_buffer_peek+0x3e0/0x430

Read of size 1 at addr ffff88802a4cf010 by task syz-executor989/6002

Freed by:

free_buffer_page kernel/trace/ring_buffer.c:398 [inline]

ring_buffer_subbuf_order_set+0x1325/0x18e0 kernel/trace/ring_buffer.c:7444

buffer_subbuf_size_write+0x182/0x280 kernel/trace/trace.c:8221

Take trace_access_lock(RING_BUFFER_ALL_CPUS) around the order change.

This is the lock trace_pipe readers already hold across their entire

peek-and-print loop, so the swap can no longer race with a reader that

is dereferencing a peeked event. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References