linux-kernel - [PATCH][next] KVM: x86: Fix bit shifting in update_intel_pt

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Date:   Wed, 26 Dec 2018 14:40:59 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Luwei Kang <luwei.kang@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH][next] KVM: x86: Fix bit shifting in update_intel_pt_cfg

ctl_bitmask in pt_desc is of type u64. When an integer like 0xf is
being left shifted more than 32 bits, the behavior is undefined.

Fix this by adding suffix ULL to integer 0xf.

Addresses-Coverity-ID: 1476095 ("Bad bit shift operation")
Fixes: 6c0f0bba85a0 ("KVM: x86: Introduce a function to initialize the PT configuration")
Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 arch/x86/kvm/vmx/vmx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index cbd55e7aeae5..251c68a74bbe 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7012,7 +7012,7 @@ static void update_intel_pt_cfg(struct kvm_vcpu *vcpu)
 
 	/* unmask address range configure area */
 	for (i = 0; i < vmx->pt_desc.addr_range; i++)
-		vmx->pt_desc.ctl_bitmask &= ~(0xf << (32 + i * 4));
+		vmx->pt_desc.ctl_bitmask &= ~(0xfULL << (32 + i * 4));
 }
 
 static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
-- 
2.20.1