On Tue, Aug 15, 2023 at 01:20:04PM +0800, Michael Shavit wrote:

On Thu, Aug 10, 2023 at 11:39 PM Jason Gunthorpe [off-list ref] wrote:

quoted

Actually, I don't think this even works as nothing on the PASID path
adds to the list that arm_smmu_write_ctx_desc_devices() iterates over ??

Then the remaining two calls:

arm_smmu_share_asid(struct mm_struct *mm, u16 asid)
        arm_smmu_write_ctx_desc_devices(smmu_domain, 0, cd);

        This is OK only if the sketchy assumption that the CD
        we extracted for a conflicting ASID is not asigned to a PASID.

static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
        arm_smmu_write_ctx_desc_devices(smmu_domain, mm->pasid, &quiet_cd);

        This doesn't work because we didn't add the master to the list
        during __arm_smmu_sva_bind and this path is expressly working
        on the PASID binds, not the RID binds.

Actually it is working on the RID attached domain (as returned by
iommu_get_domain_for_dev() at sva_bind time) not the SVA domain
here...

That can't be right, the purpose of that call and arm_smmu_mm_release is to
disable the PASID that is about the UAF the mm's page table.

Jason

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