[PATCH] KVM: arm64: Fix buffer overflow in kvm_arm_set_fw_reg()

[Dan Carpenter]

The KVM_REG_SIZE() comes from the ioctl and it can be a power of two
between 0-32768 but if it is more than sizeof(long) this will corrupt
memory.

Fixes: 99adb567632b ("KVM: arm/arm64: Add save/restore support for firmware workaround state")
Signed-off-by: Dan Carpenter <dan.carpenter at linaro.org>
---
 arch/arm64/kvm/hypercalls.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 2e16fc7b31bf..4f5767fcaca5 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -544,6 +544,8 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	u64 val;
 	int wa_level;
 
+	if (KVM_REG_SIZE(reg->id) > sizeof(val))
+		return -EINVAL;
 	if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
 		return -EFAULT;
 
-- 
2.39.2