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sink: guard against zero frame size in free-frames #10937

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sink: guard against zero frame size in free-frames #10937

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10 changes: 9 additions & 1 deletion src/module/audio/sink_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -109,7 +109,15 @@ EXPORT_SYMBOL(sink_get_frame_bytes);

size_t sink_get_free_frames(struct sof_sink *sink)
{
return sink_get_free_size(sink) / sink_get_frame_bytes(sink);
size_t frame_bytes = sink_get_frame_bytes(sink);

/* frame_bytes is channels * sample_size and both are host-influenced;
* guard against a zero divisor (e.g. channels == 0)
*/
if (!frame_bytes)

@kv2019i kv2019i Jun 18, 2026

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This is a hot-path call. Should such checks be made at prepare() stage and not on the hot path?

@lgirdwood lgirdwood Jun 18, 2026

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Agreed in principle. Two notes: the guard reuses the frame_bytes value that's already computed one line above and adds a single (well-predicted) branch, so the hot-path cost is essentially nil — the division it protects is the expensive part. But the root cause is channels_count == 0 from base_cfg reaching the audio_stream, and per my reply to Liam there's no central reject for that today. Options: (a) keep this defensive guard, or (b) reject channels_count == 0 once at module/base_cfg validation (a new central check) and drop this. (b) is the cleaner long-term fix but a broader core change. Happy to do (b) if you'd prefer — which way do you want it?

@lgirdwood lgirdwood Jun 18, 2026

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We should reject a frame size of 0 bytes before we get to this call, is there a check higher in the stack that validates this ?

@lgirdwood lgirdwood Jun 18, 2026

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I checked — there isn't a central one. sink_set_channels() stores whatever value it's given (no validation), and the only channel check in the params path (comp_buffer.c) is a mismatch check (stream channels vs params->channels), not a zero check. So a host base_cfg with channels_count == 0 currently propagates down to the audio_stream unguarded, which is what reaches this divide. There is no existing higher-stack reject.

return 0;

return sink_get_free_size(sink) / frame_bytes;
}
EXPORT_SYMBOL(sink_get_free_frames);

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