From f046923af79158361295ed4f0a588c80b9fdcc1d Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 28 Jul 2023 18:35:07 -0700 Subject: [PATCH] drm/i915/gvt: Verify pfn is "valid" before dereferencing "struct page" 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 Tested-by: Yongwei Ma Reviewed-by: Zhi Wang Link: https://lore.kernel.org/r/20230729013535.1070024-2-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- drivers/gpu/drm/i915/gvt/gtt.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c index 4ec85308379a4..58b9b316ae462 100644 --- a/drivers/gpu/drm/i915/gvt/gtt.c +++ b/drivers/gpu/drm/i915/gvt/gtt.c @@ -1183,6 +1183,10 @@ 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)); } -- 2.30.2