[PATCH] ASoC: SOF: ipc4-topology: Fix shift-out-of-bounds for aggregated ALH capture

[Peter Ujfalusi <peter.ujfalusi@linux.intel.com>]

When ch_count is smaller than blob->alh_cfg.device_count (e.g. a mono
capture stream, such as a SmartMic, aggregated across multiple SDW
links), step = ch_count / blob->alh_cfg.device_count truncates to 0.
The subsequent GENMASK(step - 1, 0) then underflows step - 1 (u32) to
UINT_MAX, causing GENMASK()'s internal shift to use an out-of-bounds
exponent:

  UBSAN: shift-out-of-bounds in sound/soc/sof/ipc4-topology.c:2363:13
  shift exponent 18446744069414584384 is too large for 64-bit type 'long unsigned int'

Treat ch_count < device_count the same way as the existing "channels
equal to output reference channels" case: apply the same ch_mask to
every aggregated device instead of trying to split channels that
can't be evenly divided.

Fixes: 0390a102cc18 ("ASoC: SOF: ipc4-topology: use different channel mask for each sdw amp feedback")
Cc: stable@vger.kernel.org
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
---
 sound/soc/sof/ipc4-topology.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/sound/soc/sof/ipc4-topology.c b/sound/soc/sof/ipc4-topology.c
index f6617dcbf789..c7ff687ecc1d 100644
--- a/sound/soc/sof/ipc4-topology.c
+++ b/sound/soc/sof/ipc4-topology.c
@@ -2473,11 +2473,14 @@ _sof_ipc4_prepare_copier_module(struct snd_sof_widget *swidget,
 				ch_map >>= 4;
 			}
 
-			if (swidget->id == snd_soc_dapm_dai_in && ch_count == out_ref_channels) {
+			if ((swidget->id == snd_soc_dapm_dai_in && ch_count == out_ref_channels) ||
+			    ch_count < blob->alh_cfg.device_count) {
 				/*
 				 * For playback DAI widgets where the channel number is equal to
-				 * the output reference channels, set the step = 0 to ensure all
-				 * the ch_mask is applied to all alh mappings.
+				 * the output reference channels, or when there are fewer
+				 * channels than aggregated devices (e.g. a mono capture
+				 * stream split across multiple links), set step = 0 to
+				 * ensure all the ch_mask is applied to all alh mappings.
 				 */
 				mask = ch_mask;
 				step = 0;
-- 
2.56.0