From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Dan Carpenter <dan.carpenter@oracle.com>
Cc: kbuild@lists.01.org, Oliver Upton <oupton@google.com>,
lkp@intel.com, kbuild-all@lists.01.org,
linux-kernel@vger.kernel.org
Subject: Re: [kbuild] arch/x86/kvm/x86.c:4988 kvm_arch_tsc_set_attr() warn: check for integer overflow 'offset'
Date: Tue, 11 Oct 2022 15:02:28 +0200 [thread overview]
Message-ID: <2c36799c-af38-fed5-3f31-a8bde25368d7@redhat.com> (raw)
In-Reply-To: <Y0Rm/Y5flhd734NX@google.com>
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
next prev parent reply other threads:[~2022-10-11 13:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-10 14:15 Dan Carpenter
2022-10-10 18:39 ` Sean Christopherson
2022-10-11 13:02 ` Paolo Bonzini [this message]
2022-10-12 6:34 ` Dan Carpenter
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