Date:   Tue, 22 Aug 2017 09:09:09 +0800
From:   nixiaoming <nixiaoming@...wei.com>
To:     <rkrcmar@...hat.com>, <pbonzini@...hat.com>
CC:     <kvm@...r.kernel.org>, <linux-api@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] virt/kvm avoids oops by adding parameter checking

The error parameter passed through the external interface causes the system oops.
So it is necessary to increase the parameter check for all EXPORT_SYMBOL_GPL

example:
 void kvm_get_kvm(struct kvm *kvm)
 {
        refcount_inc(&kvm->users_count); /*oops if kvm == NULL */
 }
 EXPORT_SYMBOL_GPL(kvm_get_kvm);

Signed-off-by: nixiaoming <nixiaoming@...wei.com>
---
 virt/kvm/eventfd.c  |  2 ++
 virt/kvm/kvm_main.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index f2ac53a..250200b 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -444,6 +444,8 @@ bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
 {
 	struct kvm_irq_ack_notifier *kian;
 	int gsi, idx;
+	if (kvm == NULL)
+		return false;
 
 	idx = srcu_read_lock(&kvm->irq_srcu);
 	gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 15252d7..3e25de0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -150,6 +150,8 @@ bool kvm_is_reserved_pfn(kvm_pfn_t pfn)
 int vcpu_load(struct kvm_vcpu *vcpu)
 {
 	int cpu;
+	if (vcpu == NULL)
+		return -EINVAL;
 
 	if (mutex_lock_killable(&vcpu->mutex))
 		return -EINTR;
@@ -163,6 +165,8 @@ EXPORT_SYMBOL_GPL(vcpu_load);
 
 void vcpu_put(struct kvm_vcpu *vcpu)
 {
+	if (vcpu == NULL)
+		return;
 	preempt_disable();
 	kvm_arch_vcpu_put(vcpu);
 	preempt_notifier_unregister(&vcpu->preempt_notifier);
@@ -235,6 +239,8 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
 #ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL
 void kvm_flush_remote_tlbs(struct kvm *kvm)
 {
+	if (kvm == NULL)
+		return;
 	/*
 	 * Read tlbs_dirty before setting KVM_REQ_TLB_FLUSH in
 	 * kvm_make_all_cpus_request.
@@ -269,6 +275,9 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
 	struct page *page;
 	int r;
 
+	if (vcpu == NULL)
+		return -EINVAL;
+
 	mutex_init(&vcpu->mutex);
 	vcpu->cpu = -1;
 	vcpu->kvm = kvm;
@@ -305,6 +314,8 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_init);
 
 void kvm_vcpu_uninit(struct kvm_vcpu *vcpu)
 {
+	if (vcpu == NULL)
+		return;
 	/*
 	 * no need for rcu_read_lock as VCPU_RUN is the only place that
 	 * will change the vcpu->pid pointer and on uninit all file
@@ -779,12 +790,16 @@ static void kvm_destroy_vm(struct kvm *kvm)
 
 void kvm_get_kvm(struct kvm *kvm)
 {
+	if (kvm == NULL)
+		return;
 	refcount_inc(&kvm->users_count);
 }
 EXPORT_SYMBOL_GPL(kvm_get_kvm);
 
 void kvm_put_kvm(struct kvm *kvm)
 {
+	if (kvm == NULL)
+		return;
 	if (refcount_dec_and_test(&kvm->users_count))
 		kvm_destroy_vm(kvm);
 }
@@ -938,6 +953,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	int as_id, id;
 	enum kvm_mr_change change;
 
+	if (mem == NULL)
+		return -EINVAL;
+
 	r = check_memory_region_flags(mem);
 	if (r)
 		goto out;
@@ -1121,6 +1139,9 @@ int kvm_get_dirty_log(struct kvm *kvm,
 	unsigned long n;
 	unsigned long any = 0;
 
+	if (log == NULL || is_dirty == NULL)
+		return -EINVAL;
+
 	as_id = log->slot >> 16;
 	id = (u16)log->slot;
 	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
@@ -1178,6 +1199,9 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
 	unsigned long *dirty_bitmap;
 	unsigned long *dirty_bitmap_buffer;
 
+	if (log == NULL || is_dirty == NULL)
+		return -EINVAL;
+
 	as_id = log->slot >> 16;
 	id = (u16)log->slot;
 	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
@@ -1996,6 +2020,8 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
 {
 	struct kvm_memslots *slots = kvm_memslots(kvm);
 	int r;
+	if (ghc == NULL)
+		return -EINVAL;
 	gpa_t gpa = ghc->gpa + offset;
 
 	BUG_ON(len + offset > ghc->len);
@@ -2225,6 +2251,8 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_block);
 bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu)
 {
 	struct swait_queue_head *wqp;
+	if (vcpu == NULL)
+		return false;
 
 	wqp = kvm_arch_vcpu_wq(vcpu);
 	if (swait_active(wqp)) {
@@ -2244,7 +2272,11 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_wake_up);
 void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
 {
 	int me;
-	int cpu = vcpu->cpu;
+	int cpu;
+
+	if (vcpu == NULL)
+		return;
+	cpu = vcpu->cpu;
 
 	if (kvm_vcpu_wake_up(vcpu))
 		return;
@@ -2264,6 +2296,9 @@ int kvm_vcpu_yield_to(struct kvm_vcpu *target)
 	struct task_struct *task = NULL;
 	int ret = 0;
 
+	if (target == NULL)
+		return -EINVAL;
+
 	rcu_read_lock();
 	pid = rcu_dereference(target->pid);
 	if (pid)
@@ -2319,13 +2354,19 @@ static bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu)
 
 void kvm_vcpu_on_spin(struct kvm_vcpu *me)
 {
-	struct kvm *kvm = me->kvm;
+	struct kvm *kvm;
 	struct kvm_vcpu *vcpu;
-	int last_boosted_vcpu = me->kvm->last_boosted_vcpu;
+	int last_boosted_vcpu;
 	int yielded = 0;
 	int try = 3;
 	int pass;
 	int i;
+	if (me == NULL)
+		return;
+	kvm = me->kvm;
+	if (kvm == NULL)
+		return;
+	last_boosted_vcpu = me->kvm->last_boosted_vcpu;
 
 	kvm_vcpu_set_in_spin_loop(me, true);
 	/*
@@ -3542,6 +3583,8 @@ static int __kvm_io_bus_read(struct kvm_vcpu *vcpu, struct kvm_io_bus *bus,
 			     struct kvm_io_range *range, void *val)
 {
 	int idx;
+	if (range == NULL)
+		return -EINVAL;
 
 	idx = kvm_io_bus_get_first_dev(bus, range->addr, range->len);
 	if (idx < 0)
@@ -3653,6 +3696,9 @@ struct kvm_io_device *kvm_io_bus_get_dev(struct kvm *kvm, enum kvm_bus bus_idx,
 	int dev_idx, srcu_idx;
 	struct kvm_io_device *iodev = NULL;
 
+	if (kvm == NULL)
+		return NULL;
+
 	srcu_idx = srcu_read_lock(&kvm->srcu);
 
 	bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
-- 
2.11.0.1

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