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

[Srinivas Kandagatla]

On 25/01/2021 10:44, Stephan Gerhold wrote:
> 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>

Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>

> ---
> 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))
>   
>