On Sat, Mar 22, 2025 at 12:56 AM Ming Lei <ming.lei@xxxxxxxxxx> wrote: > > So far fixed kernel buffer is only used for FS read/write, in which > the remained bytes need to be zeroed in case of short read, otherwise > kernel data may be leaked to userspace. I'm not sure I have all the background to understand whether kernel data can be leaked through ublk requests, but I share Pavel and Keith's questions about whether this scenario is even possible. If it is possible, I don't think this patch would cover all the affected cases: - Registered ublk buffers can be used with any io_uring operation, not just read/write. Wouldn't the same issue apply when using the ublk buffer with, say, a socket recv or an NVMe passthru operation? - Wouldn't the same issue apply if the ublk server completes a ublk read request without performing any I/O (zero-copy or not) to read data into its buffer? Best, Caleb
