[v2,1/2] kvm: x86: Bounds-check argument to x86_exception_has_error_code
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Message ID 20181015164124.225764-1-jmattson@google.com
State New
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Series
  • [v2,1/2] kvm: x86: Bounds-check argument to x86_exception_has_error_code
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Commit Message

Jim Mattson Oct. 15, 2018, 4:41 p.m. UTC
x86_exception_has_error_code should deterministically return false if
its operand is greater than 32.

Fixes: 0447378a4a793 ("kvm: vmx: Nested VM-entry prereqs for event inj.")
Cc: Marc Orr <marcorr@google.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Marc Orr <marcorr@google.com>
---
 arch/x86/kvm/x86.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Sean Christopherson Oct. 15, 2018, 4:48 p.m. UTC | #1
On Mon, Oct 15, 2018 at 09:41:23AM -0700, Jim Mattson wrote:
> x86_exception_has_error_code should deterministically return false if
> its operand is greater than 32.
> 
> Fixes: 0447378a4a793 ("kvm: vmx: Nested VM-entry prereqs for event inj.")
> Cc: Marc Orr <marcorr@google.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Jim Mattson <jmattson@google.com>
> Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
> Reviewed-by: Marc Orr <marcorr@google.com>
> ---
>  arch/x86/kvm/x86.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index 67b9568613f3..152b20d06a48 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -116,7 +116,8 @@ static inline bool x86_exception_has_error_code(unsigned int vector)
>  			BIT(NP_VECTOR) | BIT(SS_VECTOR) | BIT(GP_VECTOR) |
>  			BIT(PF_VECTOR) | BIT(AC_VECTOR);
>  
> -	return (1U << vector) & exception_has_error_code;
> +	WARN_ON_ONCE(vector >= 32);
> +	return vector < 32 && (1U << vector) & exception_has_error_code;

WARN_ON_ONCE always returns the condition, even after warning.  I.e.:

	if (WARN_ON_ONCE(vector >= 32))
		return false;
	return (1U << vector) & exception_has_error_code;

>  }
>  
>  static inline bool mmu_is_nested(struct kvm_vcpu *vcpu)
> -- 
> 2.19.1.331.ge82ca0e54c-goog
>

Patch
diff mbox series

diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 67b9568613f3..152b20d06a48 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -116,7 +116,8 @@  static inline bool x86_exception_has_error_code(unsigned int vector)
 			BIT(NP_VECTOR) | BIT(SS_VECTOR) | BIT(GP_VECTOR) |
 			BIT(PF_VECTOR) | BIT(AC_VECTOR);
 
-	return (1U << vector) & exception_has_error_code;
+	WARN_ON_ONCE(vector >= 32);
+	return vector < 32 && (1U << vector) & exception_has_error_code;
 }
 
 static inline bool mmu_is_nested(struct kvm_vcpu *vcpu)