From: Sean Christopherson <seanjc@google.com>
To: Valeriy Vdovin <valeriy.vdovin@virtuozzo.com>
Cc: linux-kernel@vger.kernel.org, Denis Lunev <den@openvz.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Shuah Khan <shuah@kernel.org>,
Aaron Lewis <aaronlewis@google.com>,
Alexander Graf <graf@amazon.com>,
Andrew Jones <drjones@redhat.com>,
Oliver Upton <oupton@google.com>,
Like Xu <like.xu@linux.intel.com>,
kvm@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v4] KVM: x86: Fix KVM_GET_CPUID2 ioctl to return cpuid entries count
Date: Thu, 29 Apr 2021 01:00:06 +0000 [thread overview]
Message-ID: <YIoFFl72VSeuhCRt@google.com> (raw)
In-Reply-To: <20210428172729.3551-1-valeriy.vdovin@virtuozzo.com>
On Wed, Apr 28, 2021, Valeriy Vdovin wrote:
> It's very explicit by the code that it was designed to receive some
> small number of entries to return E2BIG along with the corrected number.
LOL, saying KVM_GET_CPUID2 was "designed" is definitely giving the KVM
forefathers the benefit of the doubt.
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index efc7a82ab140..3f941b1f4e78 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4773,14 +4773,17 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
> r = -EFAULT;
> if (copy_from_user(&cpuid, cpuid_arg, sizeof(cpuid)))
> goto out;
> +
> r = kvm_vcpu_ioctl_get_cpuid2(vcpu, &cpuid,
> cpuid_arg->entries);
> - if (r)
> +
> + if (r && r != -E2BIG)
> goto out;
> - r = -EFAULT;
> - if (copy_to_user(cpuid_arg, &cpuid, sizeof(cpuid)))
> +
> + if (copy_to_user(cpuid_arg, &cpuid, sizeof(cpuid))) {
> + r = -EFAULT;
> goto out;
As I pointed out[*], copying the number of entries but not the entries themselves
is wrong. All of my feedback on v1 still stands.
[*] https://lkml.kernel.org/r/YIl4M/GgaYvwNuXv@google.com
> - r = 0;
> + }
> break;
> }
> case KVM_GET_MSRS: {
next prev parent reply other threads:[~2021-04-29 1:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-28 17:27 [PATCH v4] KVM: x86: Fix KVM_GET_CPUID2 ioctl to return cpuid entries count Valeriy Vdovin
2021-04-29 1:00 ` Sean Christopherson [this message]
2021-05-03 14:54 ` Paolo Bonzini
2021-05-03 19:18 ` Denis V. Lunev
2021-05-04 7:23 ` Paolo Bonzini
2021-05-04 8:15 ` Denis V. Lunev
2021-05-04 8:21 ` Paolo Bonzini
2021-05-04 9:26 ` Alexander Graf
2021-05-04 9:50 ` Paolo Bonzini
2021-05-04 16:52 ` Jim Mattson
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