On Fri, 6 Jun 2025 14:22:42 +0300 Dmitry Antipov <[email protected]> wrote:
> In 'ring_buffer_subbuf_order_set()', prefer mutex guard over explicit > mutex operations to ensure that the buffer remains locked everywhere > where its innards may be changed, thus preventing per-CPU sub-buffer > lists corruptions and other concurrency-related issues. > > Reported-by: [email protected] > Closes: https://syzkaller.appspot.com/bug?extid=05d673e83ec640f0ced9 > Fixes: f9b94daa542a8 ("ring-buffer: Set new size of the ring buffer sub page") > Signed-off-by: Dmitry Antipov <[email protected]> Looks good to me. Reviewed-by: Masami Hiramatsu (Google) <[email protected]> Thanks, > --- > v2: use mutex guard as suggested by Steven > --- > kernel/trace/ring_buffer.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index e24509bd0af5..00fc38d70e86 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -6795,7 +6795,7 @@ int ring_buffer_subbuf_order_set(struct trace_buffer > *buffer, int order) > old_size = buffer->subbuf_size; > > /* prevent another thread from changing buffer sizes */ > - mutex_lock(&buffer->mutex); > + guard(mutex)(&buffer->mutex); > atomic_inc(&buffer->record_disabled); > > /* Make sure all commits have finished */ > @@ -6900,7 +6900,6 @@ int ring_buffer_subbuf_order_set(struct trace_buffer > *buffer, int order) > } > > atomic_dec(&buffer->record_disabled); > - mutex_unlock(&buffer->mutex); > > return 0; > > @@ -6909,7 +6908,6 @@ int ring_buffer_subbuf_order_set(struct trace_buffer > *buffer, int order) > buffer->subbuf_size = old_size; > > atomic_dec(&buffer->record_disabled); > - mutex_unlock(&buffer->mutex); > > for_each_buffer_cpu(buffer, cpu) { > cpu_buffer = buffer->buffers[cpu]; > -- > 2.49.0 > -- Masami Hiramatsu (Google) <[email protected]>
