[alsa-devel] [PATCH] ASoC: Intel: Add NULL checks for the stream pointer

[Mark Brown]

On Tue, Jan 06, 2015 at 11:04:07PM +0800, Jie Yang wrote:

> We should not send IPC stream commands to FW when the stream is
> NULL, dereference the NULL pointer may also occur without precheck.
> Here add NULL pointer checks for these stream APIs.

> @@ -1420,6 +1423,9 @@ int sst_hsw_stream_commit(struct sst_hsw *hsw, struct sst_hsw_stream *stream)
>  	u32 header;
>  	int ret;
>  
> +	if (stream->commited)
> +		return 0;
> +
>  	trace_ipc_request("stream alloc", stream->host_id);
>  
>  	header = IPC_GLB_TYPE(IPC_GLB_ALLOCATE_STREAM);

This is a bit worrying, it means that we will silently ignore any
attempts to pass in a NULL stream.  Sometimes that's an OK thing to do
(like in deallocation paths) but this seems to more generally silently
ignore errors which means we're less likely to spot other coding issues.
Race conditions worry me especially - trying to use something before
we've quite allocated it for example.

I'd be much happier if this warned in cases where it wasn't totally
obvious that attempting to use a NULL pointer is sensible.
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