linux-kernel - [PATCH next] KVM: x86: Check that the high 32bits are clear in kvm_arch_vcpu_ioctl

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Message-ID: <ec25aad1-113e-4c6e-8941-43d432251398@stanley.mountain>
Date: Mon, 24 Mar 2025 13:51:28 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: Sean Christopherson <seanjc@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Pankaj Gupta <pankaj.gupta@....com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH next] KVM: x86: Check that the high 32bits are clear in
 kvm_arch_vcpu_ioctl_run()

The "kvm_run->kvm_valid_regs" and "kvm_run->kvm_dirty_regs" variables are
u64 type.  We are only using the lowest 3 bits but we want to ensure that
the users are not passing invalid bits so that we can use the remaining
bits in the future.

However "sync_valid_fields" and kvm_sync_valid_fields() are u32 type so
the check only ensures that the lower 32 bits are clear.  Fix this by
changing the types to u64.

Fixes: 74c1807f6c4f ("KVM: x86: block KVM_CAP_SYNC_REGS if guest state is protected")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 arch/x86/kvm/x86.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c841817a914a..c734ec0d809b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4597,7 +4597,7 @@ static bool kvm_is_vm_type_supported(unsigned long type)
 	return type < 32 && (kvm_caps.supported_vm_types & BIT(type));
 }
 
-static inline u32 kvm_sync_valid_fields(struct kvm *kvm)
+static inline u64 kvm_sync_valid_fields(struct kvm *kvm)
 {
 	return kvm && kvm->arch.has_protected_state ? 0 : KVM_SYNC_X86_VALID_FIELDS;
 }
@@ -11492,7 +11492,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 {
 	struct kvm_queued_exception *ex = &vcpu->arch.exception;
 	struct kvm_run *kvm_run = vcpu->run;
-	u32 sync_valid_fields;
+	u64 sync_valid_fields;
 	int r;
 
 	r = kvm_mmu_post_init_vm(vcpu->kvm);
-- 
2.47.2