From: Yan Zhao yan.y.zhao@intel.com
[ Upstream commit 4752354af71043e6fd72ef5490ed6da39e6cab4a ]
Check physical PFN is valid before converting the PFN to a struct page pointer to be returned to caller of vfio_pin_pages().
vfio_pin_pages() pins user pages with contiguous IOVA. If the IOVA of a user page to be pinned belongs to vma of vm_flags VM_PFNMAP, pin_user_pages_remote() will return -EFAULT without returning struct page address for this PFN. This is because usually this kind of PFN (e.g. MMIO PFN) has no valid struct page address associated. Upon this error, vaddr_get_pfns() will obtain the physical PFN directly.
While previously vfio_pin_pages() returns to caller PFN arrays directly, after commit 34a255e67615 ("vfio: Replace phys_pfn with pages for vfio_pin_pages()"), PFNs will be converted to "struct page *" unconditionally and therefore the returned "struct page *" array may contain invalid struct page addresses.
Given current in-tree users of vfio_pin_pages() only expect "struct page * returned, check PFN validity and return -EINVAL to let the caller be aware of IOVAs to be pinned containing PFN not able to be returned in "struct page *" array. So that, the caller will not consume the returned pointer (e.g. test PageReserved()) and avoid error like "supervisor read access in kernel mode".
Fixes: 34a255e67615 ("vfio: Replace phys_pfn with pages for vfio_pin_pages()") Cc: Sean Christopherson seanjc@google.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Yan Zhao yan.y.zhao@intel.com Reviewed-by: Sean Christopherson seanjc@google.com Link: https://lore.kernel.org/r/20230519065843.10653-1-yan.y.zhao@intel.com Signed-off-by: Alex Williamson alex.williamson@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/vfio/vfio_iommu_type1.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 7fa68dc4e938a..009ba186652ac 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -936,6 +936,11 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data, if (ret) goto pin_unwind;
+ if (!pfn_valid(phys_pfn)) { + ret = -EINVAL; + goto pin_unwind; + } + ret = vfio_add_to_pfn_list(dma, iova, phys_pfn); if (ret) { if (put_pfn(phys_pfn, dma->prot) && do_accounting)