Re: [PATCH 6/8] iommu/qcom: Add NULL ctx check in TLB invalidation paths

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 6/23/26 2:20 PM, Mukesh Ojha wrote:
> to_ctx() returns qcom_iommu->ctxs[asid], which can be NULL if the
> corresponding context bank failed to probe or was already removed.
> qcom_iommu_tlb_sync(), qcom_iommu_tlb_inv_context(), and
> qcom_iommu_tlb_inv_range_nosync() all dereference the returned pointer
> directly, risking a NULL pointer dereference.
> 
> Add WARN_ON(!ctx) guards with continue so TLB operations skip
> broken context banks without crashing.
> 
> Signed-off-by: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>
> ---
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> index 40fb0408dc07..51b60b296bb8 100644
> --- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> +++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> @@ -121,6 +121,9 @@ static void qcom_iommu_tlb_sync(void *cookie)
>  		struct qcom_iommu_ctx *ctx = to_ctx(qcom_domain, fwspec->ids[i]);
>  		unsigned int val, ret;
>  
> +		if (WARN_ON(!ctx))
> +			continue;

I'm rather unamused that we have to deal with this in the first
place.. I don't know if this can be easily reworked to be more
predictable, but this works in the interim

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad