LoongArch: KVM: Avoid overflow with array index

The variable index is modified and reused as array index when modify
register EIOINTC_ENABLE. There will be array index overflow problem.

Cc: stable@vger.kernel.org
Fixes: 3956a52 ("LoongArch: KVM: Add EIOINTC read and write functions")
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Author: bibo-mao

arch/loongarch/kvm/intc/eiointc.c

@@ -436,17 +436,16 @@ static int loongarch_eiointc_writew(struct kvm_vcpu *vcpu,
 		break;
 	case EIOINTC_ENABLE_START ... EIOINTC_ENABLE_END:
 		index = (offset - EIOINTC_ENABLE_START) >> 1;
-		old_data = s->enable.reg_u32[index];
+		old_data = s->enable.reg_u16[index];
 		s->enable.reg_u16[index] = data;
 		/*
 		 * 1: enable irq.
 		 * update irq when isr is set.
 		 */
 		data = s->enable.reg_u16[index] & ~old_data & s->isr.reg_u16[index];
-		index = index << 1;
 		for (i = 0; i < sizeof(data); i++) {
 			u8 mask = (data >> (i * 8)) & 0xff;
-			eiointc_enable_irq(vcpu, s, index + i, mask, 1);
+			eiointc_enable_irq(vcpu, s, index * 2 + i, mask, 1);
 		}
 		/*
 		 * 0: disable irq.
@@ -455,7 +454,7 @@ static int loongarch_eiointc_writew(struct kvm_vcpu *vcpu,
 		data = ~s->enable.reg_u16[index] & old_data & s->isr.reg_u16[index];
 		for (i = 0; i < sizeof(data); i++) {
 			u8 mask = (data >> (i * 8)) & 0xff;
-			eiointc_enable_irq(vcpu, s, index, mask, 0);
+			eiointc_enable_irq(vcpu, s, index * 2 + i, mask, 0);
 		}
 		break;
 	case EIOINTC_BOUNCE_START ... EIOINTC_BOUNCE_END:
@@ -529,10 +528,9 @@ static int loongarch_eiointc_writel(struct kvm_vcpu *vcpu,
 		 * update irq when isr is set.
 		 */
 		data = s->enable.reg_u32[index] & ~old_data & s->isr.reg_u32[index];
-		index = index << 2;
 		for (i = 0; i < sizeof(data); i++) {
 			u8 mask = (data >> (i * 8)) & 0xff;
-			eiointc_enable_irq(vcpu, s, index + i, mask, 1);
+			eiointc_enable_irq(vcpu, s, index * 4 + i, mask, 1);
 		}
 		/*
 		 * 0: disable irq.
@@ -541,7 +539,7 @@ static int loongarch_eiointc_writel(struct kvm_vcpu *vcpu,
 		data = ~s->enable.reg_u32[index] & old_data & s->isr.reg_u32[index];
 		for (i = 0; i < sizeof(data); i++) {
 			u8 mask = (data >> (i * 8)) & 0xff;
-			eiointc_enable_irq(vcpu, s, index, mask, 0);
+			eiointc_enable_irq(vcpu, s, index * 4 + i, mask, 0);
 		}
 		break;
 	case EIOINTC_BOUNCE_START ... EIOINTC_BOUNCE_END:
@@ -615,10 +613,9 @@ static int loongarch_eiointc_writeq(struct kvm_vcpu *vcpu,
 		 * update irq when isr is set.
 		 */
 		data = s->enable.reg_u64[index] & ~old_data & s->isr.reg_u64[index];
-		index = index << 3;
 		for (i = 0; i < sizeof(data); i++) {
 			u8 mask = (data >> (i * 8)) & 0xff;
-			eiointc_enable_irq(vcpu, s, index + i, mask, 1);
+			eiointc_enable_irq(vcpu, s, index * 8 + i, mask, 1);
 		}
 		/*
 		 * 0: disable irq.
@@ -627,7 +624,7 @@ static int loongarch_eiointc_writeq(struct kvm_vcpu *vcpu,
 		data = ~s->enable.reg_u64[index] & old_data & s->isr.reg_u64[index];
 		for (i = 0; i < sizeof(data); i++) {
 			u8 mask = (data >> (i * 8)) & 0xff;
-			eiointc_enable_irq(vcpu, s, index, mask, 0);
+			eiointc_enable_irq(vcpu, s, index * 8 + i, mask, 0);
 		}
 		break;
 	case EIOINTC_BOUNCE_START ... EIOINTC_BOUNCE_END: