linux-kernel - [PATCH] kvm/x86: actually verify that reading MSR_IA32_UCODE

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Message-Id: <20230315195109.580333-1-d-tatianin@yandex-team.ru>
Date:   Wed, 15 Mar 2023 22:51:09 +0300
From:   Daniil Tatianin <d-tatianin@...dex-team.ru>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Daniil Tatianin <d-tatianin@...dex-team.ru>,
        Paolo Bonzini <pbonzini@...hat.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>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] kvm/x86: actually verify that reading MSR_IA32_UCODE_REV succeeds

...and return KVM_MSR_RET_INVALID otherwise.

Found by Linux Verification Center (linuxtesting.org) with the SVACE
static analysis tool.

Fixes: cd28325249a1 ("KVM: VMX: support MSR_IA32_ARCH_CAPABILITIES as a feature MSR")
Signed-off-by: Daniil Tatianin <d-tatianin@...dex-team.ru>
---
 arch/x86/kvm/x86.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7713420abab0..7de6939fc371 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1661,7 +1661,8 @@ static int kvm_get_msr_feature(struct kvm_msr_entry *msr)
 		msr->data = kvm_caps.supported_perf_cap;
 		break;
 	case MSR_IA32_UCODE_REV:
-		rdmsrl_safe(msr->index, &msr->data);
+		if (rdmsrl_safe(msr->index, &msr->data))
+			return KVM_MSR_RET_INVALID;
 		break;
 	default:
 		return static_call(kvm_x86_get_msr_feature)(msr);
-- 
2.25.1