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05 April 2024, 19:05:47 UTC
Revision 5c49d1850ddd3240d20dc40b01f593e35a184f38 authored by Zhenzhong Duan on 26 September 2021, 01:55:45 UTC, committed by Paolo Bonzini on 27 September 2021, 15:25:40 UTC 
KVM: VMX: Fix a TSX_CTRL_CPUID_CLEAR field mask issue
 
When updating the host's mask for its MSR_IA32_TSX_CTRL user return entry,
clear the mask in the found uret MSR instead of vmx->guest_uret_msrs[i].
Modifying guest_uret_msrs directly is completely broken as 'i' does not
point at the MSR_IA32_TSX_CTRL entry.  In fact, it's guaranteed to be an
out-of-bounds accesses as is always set to kvm_nr_uret_msrs in a prior
loop. By sheer dumb luck, the fallout is limited to "only" failing to
preserve the host's TSX_CTRL_CPUID_CLEAR.  The out-of-bounds access is
benign as it's guaranteed to clear a bit in a guest MSR value, which are
always zero at vCPU creation on both x86-64 and i386.

Cc: stable@vger.kernel.org
Fixes: 8ea8b8d6f869 ("KVM: VMX: Use common x86's uret MSR list as the one true list")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210926015545.281083-1-zhenzhong.duan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 parent 50b0781
History
Tip revision: 5c49d1850ddd3240d20dc40b01f593e35a184f38 authored by Zhenzhong Duan on 26 September 2021, 01:55:45 UTC
KVM: VMX: Fix a TSX_CTRL_CPUID_CLEAR field mask issue
Tip revision: 5c49d18
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