Patch-mainline: v5.19-rc8
Git-commit: cf5029d5dd7cb0aaa53250fa9e389abd231606b3
References: git-fixes
From: Aaron Lewis <aaronlewis@google.com>
Date: Thu, 14 Jul 2022 16:13:15 +0000
Subject: [PATCH] KVM: x86: Protect the unused bits in MSR exiting flags

The flags for KVM_CAP_X86_USER_SPACE_MSR and KVM_X86_SET_MSR_FILTER
have no protection for their unused bits.  Without protection, future
development for these features will be difficult.  Add the protection
needed to make it possible to extend these features in the future.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Message-Id: <20220714161314.1715227-1-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/kvm/x86.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 143e37298d8a..e5fa335a4ea7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6029,6 +6029,11 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 		r = 0;
 		break;
 	case KVM_CAP_X86_USER_SPACE_MSR:
+		r = -EINVAL;
+		if (cap->args[0] & ~(KVM_MSR_EXIT_REASON_INVAL |
+				     KVM_MSR_EXIT_REASON_UNKNOWN |
+				     KVM_MSR_EXIT_REASON_FILTER))
+			break;
 		kvm->arch.user_space_msr_mask = cap->args[0];
 		r = 0;
 		break;
@@ -6183,6 +6188,9 @@ static int kvm_vm_ioctl_set_msr_filter(struct kvm *kvm, void __user *argp)
 	if (copy_from_user(&filter, user_msr_filter, sizeof(filter)))
 		return -EFAULT;
 
+	if (filter.flags & ~KVM_MSR_FILTER_DEFAULT_DENY)
+		return -EINVAL;
+
 	for (i = 0; i < ARRAY_SIZE(filter.ranges); i++)
 		empty &= !filter.ranges[i].nmsrs;
 
-- 
2.35.3