[PATCH v2 4/7] LoongArch: KVM: Check validation of num_cpu from user space

[Bibo Mao <maobibo@xxxxxxxxxxx>]

The maximum supported cpu number is EIOINTC_ROUTE_MAX_VCPUS about
irqchip eiointc, here add validation about cpu number to avoid array
pointer overflow.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 1ad7efa552fd ("LoongArch: KVM: Add EIOINTC user mode read and write functions")
Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
---
 arch/loongarch/kvm/intc/eiointc.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/arch/loongarch/kvm/intc/eiointc.c b/arch/loongarch/kvm/intc/eiointc.c
index b48511f903b5..ed80bf290755 100644
--- a/arch/loongarch/kvm/intc/eiointc.c
+++ b/arch/loongarch/kvm/intc/eiointc.c
@@ -798,7 +798,7 @@ static int kvm_eiointc_ctrl_access(struct kvm_device *dev,
 	int ret = 0;
 	unsigned long flags;
 	unsigned long type = (unsigned long)attr->attr;
-	u32 i, start_irq;
+	u32 i, start_irq, val;
 	void __user *data;
 	struct loongarch_eiointc *s = dev->kvm->arch.eiointc;
 
@@ -806,7 +806,12 @@ static int kvm_eiointc_ctrl_access(struct kvm_device *dev,
 	spin_lock_irqsave(&s->lock, flags);
 	switch (type) {
 	case KVM_DEV_LOONGARCH_EXTIOI_CTRL_INIT_NUM_CPU:
-		if (copy_from_user(&s->num_cpu, data, 4))
+		if (copy_from_user(&val, data, 4) == 0) {
+			if (val < EIOINTC_ROUTE_MAX_VCPUS)
+				s->num_cpu = val;
+			else
+				ret = -EINVAL;
+		} else
 			ret = -EFAULT;
 		break;
 	case KVM_DEV_LOONGARCH_EXTIOI_CTRL_INIT_FEATURE:
@@ -835,7 +840,7 @@ static int kvm_eiointc_regs_access(struct kvm_device *dev,
 					struct kvm_device_attr *attr,
 					bool is_write)
 {
-	int addr, cpuid, offset, ret = 0;
+	int addr, cpu, offset, ret = 0;
 	unsigned long flags;
 	void *p = NULL;
 	void __user *data;
@@ -843,7 +848,7 @@ static int kvm_eiointc_regs_access(struct kvm_device *dev,
 
 	s = dev->kvm->arch.eiointc;
 	addr = attr->attr;
-	cpuid = addr >> 16;
+	cpu = addr >> 16;
 	addr &= 0xffff;
 	data = (void __user *)attr->addr;
 	switch (addr) {
@@ -868,8 +873,11 @@ static int kvm_eiointc_regs_access(struct kvm_device *dev,
 		p = &s->isr.reg_u32[offset];
 		break;
 	case EIOINTC_COREISR_START ... EIOINTC_COREISR_END:
+		if (cpu >= s->num_cpu)
+			return -EINVAL;
+
 		offset = (addr - EIOINTC_COREISR_START) / 4;
-		p = &s->coreisr.reg_u32[cpuid][offset];
+		p = &s->coreisr.reg_u32[cpu][offset];
 		break;
 	case EIOINTC_COREMAP_START ... EIOINTC_COREMAP_END:
 		offset = (addr - EIOINTC_COREMAP_START) / 4;
-- 
2.39.3