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From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: DRI Development <dri-devel@lists.freedesktop.org>,
	LKML <linux-kernel@vger.kernel.org>
Cc: linux-samsung-soc@vger.kernel.org, "Jan Kara" <jack@suse.cz>,
	"Kees Cook" <keescook@chromium.org>,
	kvm@vger.kernel.org, "Jason Gunthorpe" <jgg@ziepe.ca>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Cornelia Huck" <cohuck@redhat.com>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	linux-mm@kvack.org, "Jérôme Glisse" <jglisse@redhat.com>,
	"John Hubbard" <jhubbard@nvidia.com>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org
Subject: [PATCH v7 15/17] vfio/type1: Mark follow_pfn as unsafe
Date: Fri, 27 Nov 2020 17:41:29 +0100
Message-ID: <20201127164131.2244124-16-daniel.vetter@ffwll.ch> (raw)
In-Reply-To: <20201127164131.2244124-1-daniel.vetter@ffwll.ch>

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@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kees Cook <keescook@chromium.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: kvm@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.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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  parent reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-27 16:41 [PATCH v7 00/17] follow_pfn and other iomap races Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 01/17] drm/exynos: Stop using frame_vector helpers Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 02/17] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 03/17] misc/habana: Stop using frame_vector helpers Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 04/17] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 05/17] mm/frame-vector: Use FOLL_LONGTERM Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 06/17] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 07/17] mm: Close race in generic_access_phys Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 08/17] PCI: Obey iomem restrictions for procfs mmap Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 09/17] /dev/mem: Only set filp->f_mapping Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 10/17] resource: Move devmem revoke code to resource framework Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 11/17] sysfs: Support zapping of binary attr mmaps Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 12/17] PCI: Revoke mappings like devmem Daniel Vetter
2021-01-19  8:17   ` Daniel Vetter
2021-01-19 14:32     ` Greg Kroah-Hartman
2021-01-19 14:34       ` Daniel Vetter
2021-01-19 15:20         ` Greg Kroah-Hartman
2021-01-19 16:03           ` Daniel Vetter
2021-02-03 16:14             ` Daniel Vetter
2021-02-04 10:23               ` Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 13/17] mm: Add unsafe_follow_pfn Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 14/17] media/videobuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter
2021-01-19 12:24   ` Hans Verkuil
2020-11-27 16:41 ` Daniel Vetter [this message]
2020-11-27 16:41 ` [PATCH v7 16/17] kvm: pass kvm argument to follow_pfn callsites Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 17/17] mm: add mmu_notifier argument to follow_pfn Daniel Vetter
2020-11-27 19:10   ` kernel test robot
2020-11-30 14:28     ` Daniel Vetter
2020-11-30 18:03       ` Nick Desaulniers
2021-01-12 13:24 ` [PATCH v7 00/17] follow_pfn and other iomap races Daniel Vetter
2021-01-12 13:28   ` Daniel Vetter
2021-01-12 20:57   ` Stephen Rothwell

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