CVE-2026-89747 is a vulnerability in Linux Kernel
Published on September 11, 2026
tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
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.
Products Associated with CVE-2026-89747
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Affected Versions
Linux:- Version f9b94daa542a8d2532f0930f01cd9aec2d19621b and below 05ebe1e1d7d38c2612bacfefe043a33572ae34cb is affected.
- Version f9b94daa542a8d2532f0930f01cd9aec2d19621b and below ddbe921ed16a0ad2d9e09574c3f3aabec7528325 is affected.
- Version f9b94daa542a8d2532f0930f01cd9aec2d19621b and below 7a49d19ff9baaf61217e5ec14199c18bc2d93ee4 is affected.
- Version f9b94daa542a8d2532f0930f01cd9aec2d19621b and below 372f8534244d632ad5118e8a87a11291b01712d3 is affected.
- Version 6.8 is affected.
- Before 6.8 is unaffected.
- Version 6.12.109, <= 6.12.* is unaffected.
- Version 6.18.50, <= 6.18.* is unaffected.
- Version 7.2.4, <= 7.2.* is unaffected.
- Version 7.3-rc1, <= * is unaffected.