RE: [PATCH] iommufd: Set domain->iommufd_hwpt in all hwpt->domain allocators

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Thursday, March 6, 2025 5:18 AM
> 
> Setting domain->iommufd_hwpt in iommufd_hwpt_alloc() only covers the
> HWPT
> allocations from user space, but not for an auto domain. This resulted in
> a NULL pointer access in the auto domain pathway:
>  Unable to handle kernel NULL pointer dereference at
>  	virtual address 0000000000000008
>  pc : iommufd_sw_msi+0x54/0x2b0
>  lr : iommufd_sw_msi+0x40/0x2b0
>  Call trace:
>   iommufd_sw_msi+0x54/0x2b0 (P)
>   iommu_dma_prepare_msi+0x64/0xa8
>   its_irq_domain_alloc+0xf0/0x2c0
>   irq_domain_alloc_irqs_parent+0x2c/0xa8
>   msi_domain_alloc+0xa0/0x1a8
> 
> Since iommufd_sw_msi() requires to access the domain->iommufd_hwpt, it
> is
> better to set that explicitly prior to calling iommu_domain_set_sw_msi().
> 
> Fixes: 748706d7ca06 ("iommu: Turn fault_data to iommufd private pointer")
> Reported-by: Ankit Agrawal <ankita@xxxxxxxxxx>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>