KVM: arm64: vgic-its: Add a data length check in vgic_its_save_*

In all the vgic_its_save_*() functinos, they do not check whether
the data length is 8 bytes before calling vgic_write_guest_lock.
This patch adds the check. To prevent the kernel from being blown up
when the fault occurs, KVM_BUG_ON() is used. And the other BUG_ON()s
are replaced together.

Cc: stable@vger.kernel.org
Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
[Jing: Update with the new entry read/write helpers]
Signed-off-by: Jing Zhang <jingzhangos@google.com>
Link: https://lore.kernel.org/r/20241107214137.428439-4-jingzhangos@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

arch/arm64/kvm/vgic/vgic-its.c

@@ -2086,7 +2086,6 @@ static int scan_its_table(struct vgic_its *its, gpa_t base, int size, u32 esz,
 static int vgic_its_save_ite(struct vgic_its *its, struct its_device *dev,
 			      struct its_ite *ite, gpa_t gpa, int ite_esz)
 {
-	struct kvm *kvm = its->dev->kvm;
 	u32 next_offset;
 	u64 val;
 
@@ -2095,7 +2094,8 @@ static int vgic_its_save_ite(struct vgic_its *its, struct its_device *dev,
 	       ((u64)ite->irq->intid << KVM_ITS_ITE_PINTID_SHIFT) |
 		ite->collection->collection_id;
 	val = cpu_to_le64(val);
-	return vgic_write_guest_lock(kvm, gpa, &val, ite_esz);
+
+	return vgic_its_write_entry_lock(its, gpa, val, ite_esz);
 }
 
 /**
@@ -2239,7 +2239,6 @@ static int vgic_its_restore_itt(struct vgic_its *its, struct its_device *dev)
 static int vgic_its_save_dte(struct vgic_its *its, struct its_device *dev,
 			     gpa_t ptr, int dte_esz)
 {
-	struct kvm *kvm = its->dev->kvm;
 	u64 val, itt_addr_field;
 	u32 next_offset;
 
@@ -2250,7 +2249,8 @@ static int vgic_its_save_dte(struct vgic_its *its, struct its_device *dev,
 	       (itt_addr_field << KVM_ITS_DTE_ITTADDR_SHIFT) |
 		(dev->num_eventid_bits - 1));
 	val = cpu_to_le64(val);
-	return vgic_write_guest_lock(kvm, ptr, &val, dte_esz);
+
+	return vgic_its_write_entry_lock(its, ptr, val, dte_esz);
 }
 
 /**
@@ -2437,7 +2437,8 @@ static int vgic_its_save_cte(struct vgic_its *its,
 	       ((u64)collection->target_addr << KVM_ITS_CTE_RDBASE_SHIFT) |
 	       collection->collection_id);
 	val = cpu_to_le64(val);
-	return vgic_write_guest_lock(its->dev->kvm, gpa, &val, esz);
+
+	return vgic_its_write_entry_lock(its, gpa, val, esz);
 }
 
 /*
@@ -2453,8 +2454,7 @@ static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz)
 	u64 val;
 	int ret;
 
-	BUG_ON(esz > sizeof(val));
+	ret = vgic_its_read_entry_lock(its, gpa, &val, esz);
-	ret = kvm_read_guest_lock(kvm, gpa, &val, esz);
 	if (ret)
 		return ret;
 	val = le64_to_cpu(val);
@@ -2492,7 +2492,6 @@ static int vgic_its_save_collection_table(struct vgic_its *its)
 	u64 baser = its->baser_coll_table;
 	gpa_t gpa = GITS_BASER_ADDR_48_to_52(baser);
 	struct its_collection *collection;
-	u64 val;
 	size_t max_size, filled = 0;
 	int ret, cte_esz = abi->cte_esz;
 
@@ -2516,10 +2515,7 @@ static int vgic_its_save_collection_table(struct vgic_its *its)
 	 * table is not fully filled, add a last dummy element
 	 * with valid bit unset
 	 */
-	val = 0;
+	return vgic_its_write_entry_lock(its, gpa, 0, cte_esz);
-	BUG_ON(cte_esz > sizeof(val));
-	ret = vgic_write_guest_lock(its->dev->kvm, gpa, &val, cte_esz);
-	return ret;
 }
 
 /*

arch/arm64/kvm/vgic/vgic.h

@@ -146,6 +146,29 @@ static inline int vgic_write_guest_lock(struct kvm *kvm, gpa_t gpa,
 	return ret;
 }
 
+static inline int vgic_its_read_entry_lock(struct vgic_its *its, gpa_t eaddr,
+					   u64 *eval, unsigned long esize)
+{
+	struct kvm *kvm = its->dev->kvm;
+
+	if (KVM_BUG_ON(esize != sizeof(*eval), kvm))
+		return -EINVAL;
+
+	return kvm_read_guest_lock(kvm, eaddr, eval, esize);
+
+}
+
+static inline int vgic_its_write_entry_lock(struct vgic_its *its, gpa_t eaddr,
+					    u64 eval, unsigned long esize)
+{
+	struct kvm *kvm = its->dev->kvm;
+
+	if (KVM_BUG_ON(esize != sizeof(eval), kvm))
+		return -EINVAL;
+
+	return vgic_write_guest_lock(kvm, eaddr, &eval, esize);
+}
+
 /*
  * This struct provides an intermediate representation of the fields contained
  * in the GICH_VMCR and ICH_VMCR registers, such that code exporting the GIC