Messages in this thread Patch in this message | | | From | Paolo Bonzini <> | Subject | [PATCH] KVM: x86: remove bogus user-triggerable WARN_ON | Date | Thu, 19 Mar 2020 13:43:18 -0400 |
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The WARN_ON is essentially comparing a user-provided value with 0. It is trivial to trigger it just by passing garbage to KVM_SET_CLOCK. Guests can break if you do so, but if it hurts when you do like this just do not do it.
Reported-by: syzbot+00be5da1d75f1cc95f6b@syzkaller.appspotmail.com Fixes: 9446e6fce0ab ("KVM: x86: fix WARN_ON check of an unsigned less than zero") Cc: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/x86.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3156e25b0774..d65ff2008cf1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2444,7 +2444,6 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) vcpu->hv_clock.tsc_timestamp = tsc_timestamp; vcpu->hv_clock.system_time = kernel_ns + v->kvm->arch.kvmclock_offset; vcpu->last_guest_tsc = tsc_timestamp; - WARN_ON((s64)vcpu->hv_clock.system_time < 0); /* If the host uses TSC clocksource, then it is stable */ pvclock_flags = 0; -- 2.18.2
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