From: Sean Christopherson <seanjc@google.com>
Date: Sat, 29 Jul 2023 01:35:07 +0000 (-0700)
Subject: drm/i915/gvt: Verify pfn is "valid" before dereferencing "struct page"
X-Git-Tag: v6.1.61~1103
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f5738399ed965be3ba734bd039bf96a455bb5ac0;p=platform%2Fkernel%2Flinux-starfive.git

drm/i915/gvt: Verify pfn is "valid" before dereferencing "struct page"

[ Upstream commit f046923af79158361295ed4f0a588c80b9fdcc1d ]

Check that the pfn found by gfn_to_pfn() is actually backed by "struct
page" memory prior to retrieving and dereferencing the page.  KVM
supports backing guest memory with VM_PFNMAP, VM_IO, etc., and so
there is no guarantee the pfn returned by gfn_to_pfn() has an associated
"struct page".

Fixes: b901b252b6cf ("drm/i915/gvt: Add 2M huge gtt support")
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index 80c6075..92462cd 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -1188,6 +1188,10 @@ static int is_2MB_gtt_possible(struct intel_vgpu *vgpu,
 	pfn = gfn_to_pfn(vgpu->vfio_device.kvm, ops->get_pfn(entry));
 	if (is_error_noslot_pfn(pfn))
 		return -EINVAL;
+
+	if (!pfn_valid(pfn))
+		return -EINVAL;
+
 	return PageTransHuge(pfn_to_page(pfn));
 }