Re: [PATCH v3] iommu/riscv: prevent NULL deref in iova_to_phys

[Robin Murphy]

On 15/08/2025 11:01 am, Joerg Roedel wrote:
> On Fri, Aug 15, 2025 at 03:12:44PM +0800, XianLiang Huang wrote:
> > diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
> > index 2d0d31ba2886..0eae2f4bdc5e 100644
> > --- a/drivers/iommu/riscv/iommu.c
> > +++ b/drivers/iommu/riscv/iommu.c
> > @@ -1283,7 +1283,7 @@ static phys_addr_t riscv_iommu_iova_to_phys(struct iommu_domain *iommu_domain,
> >   	unsigned long *ptr;
> >   
> >   	ptr = riscv_iommu_pte_fetch(domain, iova, &pte_size);
> > -	if (_io_pte_none(*ptr) || !_io_pte_present(*ptr))
> > +	if (!ptr)
> >   		return 0;
>
> Zero is usually not an invalid physical address, or is it on RISC-V?

It's a valid PA on many systems of many architectures, but it's also 
been the "not mapped/error" value for the iova_to_phys operation all the 
way back to the very very first intel_iommu_iova_to_pfn() nearly 17 
years ago, so hey :)

Thanks,
Robin.