Re: STABLE REQ: [PATCH v5 06/10] tracing: Fix subbuf resize races with trace_pipe_raw readers

On Tue, Sep 01, 2026 at 01:34:44PM +0100, Lee Jones wrote:

Dear Stable,

quoted

Concurrent subbuffer resizes may crash trace_pipe_raw readers or leak
uninitialized memory to userspace due to stale size values.

Modify ring_buffer_alloc_read_page() to let it handle the resizing of
a previous buffer_data_read_page if necessary and add a new
ring_buffer_read_page_size() which enable ring-buffer users to not use
the racy ring_buffer_subbuf_size_get(). This makes the spare_size member
of ftrace_buffer_info redundant.

Use those functions in trace_pipe_raw readers and handle in both the
case where the subbuf order is modified in the middle of the read.

Fixes: bce761d75745 ("ring-buffer: Read and write to ring buffers with custom sub buffer size")
Signed-off-by: Vincent Donnefort <redacted>

Not sure if this is the latest version or not?

I see review comments, but no v6.  Anyway, no matter, it'll do.

Could we have this applied to Stable please:

8a5f63637890 ("ring-buffer: Fix subbuf resize race with ring buffer readers")

-- 
Lee Jones

Steven hasn't taken all the patches from v5, a few of them were not ready yet.

The latest version is v8 [1]... and I am about to send a v9.

[1] https://lore.kernel.org/all/20260826094528.3738023-1-vdonnefort@google.com/ (local) 

-- 
Vincent