Re: [PATCH v33 10/18] ALSA: virtio: Keep control payloads alive through DMA completion

[sashiko-bot@kernel.org]

> From: Joonho Lee <mynameisjune111@gmail.com>
> 
> Control requests can expose caller-owned payloads to the device after a
> synchronous send times out. Keep request and response headers and
> payloads in the reference-counted message so caller cleanup cannot
> invalidate DMA.
> 
> Keep the queue reference until device completion or post-reset cleanup,
> even when the caller times out or is interrupted. Consume the caller's
> reference on every send path, and let response readers retain an extra
> reference through copyout. Check payload sizes and allocation arithmetic
> before building the scatterlists.
> 
> A control value payload is also read by the CPU as a typed structure.
> DMA cacheline alignment alone does not guarantee the structure's CPU
> alignment. Align regions to the greater of the DMA cacheline and
> control-value type alignment, and reserve prefix slack from the buffer
> base so typed accesses remain aligned while scatterlist regions stay on
> cacheline boundaries.
> 
> Keep response values in a separately allocated aligned response buffer
> so INTEGER64 control accesses are aligned from this patch onward.
> 
> Fixes: 9d45e514da88 ("ALSA: virtio: handling control messages")
> Assisted-by: LLM
> Signed-off-by: Joonho Lee <mynameisjune111@gmail.com>

Sashiko has reviewed this patch and found no issues.

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