[PATCH v2] ASoC: qcom: lpass: Fix out-of-bounds DAI ID lookup

[Stephan Gerhold]

The "dai_id" given into LPAIF_INTFDMA_REG(...) is already the real
DAI ID, not an index into v->dai_driver. Looking it up again seems
entirely redundant.

For IPQ806x (and SC7180 since commit 09a4f6f5d21c
("ASoC: dt-bindings: lpass: Fix and common up lpass dai ids") this is
now often an out-of-bounds read because the indexes in the "dai_driver"
array no longer match the actual DAI ID.

Cc: Srinivasa Rao Mandadapu <srivasam at codeaurora.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>
Fixes: 7cb37b7bd0d3 ("ASoC: qcom: Add support for lpass hdmi driver")
Signed-off-by: Stephan Gerhold <stephan at gerhold.net>
---
Changes in v2:
  - Extracted from https://lore.kernel.org/alsa-devel/20210114094615.58191-2-stephan@gerhold.net/
  - Change commit message to clarify that this is usually not just
    redundant now but actually a broken out-of-bounds lookup.
---
 sound/soc/qcom/lpass-lpaif-reg.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/qcom/lpass-lpaif-reg.h b/sound/soc/qcom/lpass-lpaif-reg.h
index 405542832e99..baf72f124ea9 100644
--- a/sound/soc/qcom/lpass-lpaif-reg.h
+++ b/sound/soc/qcom/lpass-lpaif-reg.h
@@ -133,7 +133,7 @@
 #define	LPAIF_WRDMAPERCNT_REG(v, chan)	LPAIF_WRDMA_REG_ADDR(v, 0x14, (chan))
 
 #define LPAIF_INTFDMA_REG(v, chan, reg, dai_id)  \
-		((v->dai_driver[dai_id].id ==  LPASS_DP_RX) ? \
+	((dai_id ==  LPASS_DP_RX) ? \
 		LPAIF_HDMI_RDMA##reg##_REG(v, chan) : \
 		 LPAIF_RDMA##reg##_REG(v, chan))
 
-- 
2.30.0