From d33294541889b023068522270cd4153ddd8e4635 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 19 Mar 2020 13:41:06 -0400 Subject: KVM: x86: remove bogus user-triggerable WARN_ON 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 the same applies to every KVM_SET_* ioctl. So, 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 Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 1 - 1 file changed, 1 deletion(-) (limited to 'arch') 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; -- cgit v1.2.3