From: Jike Song <jike.song@intel.com>
Date: Fri, 16 Dec 2016 02:51:05 +0000 (+0800)
Subject: drm/i915/gvt/kvmgt: check returned slot for gfn
X-Git-Tag: v4.10-rc3~19^2~8^2~4
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=faaaa53bdc6750c438887d44f99b60ad97ec74b4;p=linux.git

drm/i915/gvt/kvmgt: check returned slot for gfn

gfn_to_memslot() may return NULL if the gfn is mmio
or invalid. A malicious user might input a bad gfn
to panic the host if we don't check it.

Signed-off-by: Jike Song <jike.song@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
---

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 4ba196796846..8b3b071a535e 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -1137,6 +1137,10 @@ static int kvmgt_write_protect_add(unsigned long handle, u64 gfn)
 
 	idx = srcu_read_lock(&kvm->srcu);
 	slot = gfn_to_memslot(kvm, gfn);
+	if (!slot) {
+		srcu_read_unlock(&kvm->srcu, idx);
+		return -EINVAL;
+	}
 
 	spin_lock(&kvm->mmu_lock);
 
@@ -1167,6 +1171,10 @@ static int kvmgt_write_protect_remove(unsigned long handle, u64 gfn)
 
 	idx = srcu_read_lock(&kvm->srcu);
 	slot = gfn_to_memslot(kvm, gfn);
+	if (!slot) {
+		srcu_read_unlock(&kvm->srcu, idx);
+		return -EINVAL;
+	}
 
 	spin_lock(&kvm->mmu_lock);