Re: [kbuild] arch/x86/kvm/x86.c:4988 kvm_arch_tsc_set_attr() warn: check for integer overflow 'offset'

[Paolo Bonzini]

On 10/10/22 20:39, Sean Christopherson wrote:
> > 828ca89628bfcb Oliver Upton 2021-09-16 @4988  		tsc = kvm_scale_tsc(vcpu, rdtsc(), vcpu->arch.l1_tsc_scaling_ratio) + offset;
> >
> > Smatch hates obvious user triggerable integer overflows...  No checking
> > on offset.
>
> This is ok, and even necessary, e.g. if the host TSC > guest TSC.

(which in fact is the common case).  Also this is unsigned which is fine 
according to the C standard, though I understand that static analyzers 
want to be stricter.

> Is there anything
> we can do in KVM to help Smatch avoid false positives?  Or do you/Smatch already
> maintain a list of known false positives?

Seconded.

Paolo