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Date: Fri, 27 Nov 2020 17:41:29 +0100 From: Daniel Vetter <daniel.vetter@...ll.ch> To: DRI Development <dri-devel@...ts.freedesktop.org>, LKML <linux-kernel@...r.kernel.org> Cc: kvm@...r.kernel.org, linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, linux-media@...r.kernel.org, Daniel Vetter <daniel.vetter@...ll.ch>, Daniel Vetter <daniel.vetter@...el.com>, Jason Gunthorpe <jgg@...pe.ca>, Kees Cook <keescook@...omium.org>, Dan Williams <dan.j.williams@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, John Hubbard <jhubbard@...dia.com>, Jérôme Glisse <jglisse@...hat.com>, Jan Kara <jack@...e.cz>, Alex Williamson <alex.williamson@...hat.com>, Cornelia Huck <cohuck@...hat.com> Subject: [PATCH v7 15/17] vfio/type1: Mark follow_pfn as unsafe The code seems to stuff these pfns into iommu pts (or something like that, I didn't follow), but there's no mmu_notifier to ensure that access is synchronized with pte updates. Hence mark these as unsafe. This means that with CONFIG_STRICT_FOLLOW_PFN, these will be rejected. Real fix is to wire up an mmu_notifier ... somehow. Probably means any invalidate is a fatal fault for this vfio device, but then this shouldn't ever happen if userspace is reasonable. Signed-off-by: Daniel Vetter <daniel.vetter@...el.com> Cc: Jason Gunthorpe <jgg@...pe.ca> Cc: Kees Cook <keescook@...omium.org> Cc: Dan Williams <dan.j.williams@...el.com> Cc: Andrew Morton <akpm@...ux-foundation.org> Cc: John Hubbard <jhubbard@...dia.com> Cc: Jérôme Glisse <jglisse@...hat.com> Cc: Jan Kara <jack@...e.cz> Cc: Dan Williams <dan.j.williams@...el.com> Cc: linux-mm@...ck.org Cc: linux-arm-kernel@...ts.infradead.org Cc: linux-samsung-soc@...r.kernel.org Cc: linux-media@...r.kernel.org Cc: Alex Williamson <alex.williamson@...hat.com> Cc: Cornelia Huck <cohuck@...hat.com> Cc: kvm@...r.kernel.org Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch> --- drivers/vfio/vfio_iommu_type1.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 67e827638995..10170723bb58 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -421,7 +421,7 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm, { int ret; - ret = follow_pfn(vma, vaddr, pfn); + ret = unsafe_follow_pfn(vma, vaddr, pfn); if (ret) { bool unlocked = false; @@ -435,7 +435,7 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm, if (ret) return ret; - ret = follow_pfn(vma, vaddr, pfn); + ret = unsafe_follow_pfn(vma, vaddr, pfn); } return ret; -- 2.29.2
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