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From: Andi Kleen <andi@firstfloor.org>
To: ehankland@google.com
Cc: linux-kernel@vger.kernel.org, linux-kvm@vger.kernel.org
Subject: Re: [PATCH v1] KVM: x86: PMU Whitelist
Date: Thu, 20 Jun 2019 11:05:01 -0700	[thread overview]
Message-ID: <877e9g9lpu.fsf@firstfloor.org> (raw)
In-Reply-To: <CAOyeoRWfPNmaWY6Lifdkdj3KPPM654vzDO+s3oduEMCJP+Asow@mail.gmail.com> (Eric Hankland's message of "Wed, 22 May 2019 15:23:00 -0700")

Eric Hankland <ehankland@google.com> writes:
>
> +int kvm_vcpu_ioctl_set_pmu_whitelist(struct kvm_vcpu *vcpu,
> +                                    struct kvm_pmu_whitelist __user *whtlst)
> +{
> +       struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
> +       struct kvm_pmu_whitelist *old = pmu->whitelist;
> +       struct kvm_pmu_whitelist *new = NULL;
> +       struct kvm_pmu_whitelist tmp;
> +       int r;
> +       size_t size;
> +
> +       r = -EFAULT;
> +       if (copy_from_user(&tmp, whtlst, sizeof(struct kvm_pmu_whitelist)))
> +               goto err;
> +
> +       size = sizeof(tmp) + sizeof(tmp.events[0]) * tmp.num_events;
> +       new = kvzalloc(size, GFP_KERNEL_ACCOUNT);

Consider what happens when tmp.num_events is large enough to wrap size.
I suspect that's a kernel exploit as written.

Also don't you need to copy tmp to new?

-Andi


  parent reply	other threads:[~2019-06-20 18:27 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22 22:23 [PATCH v1] KVM: x86: PMU Whitelist Eric Hankland
2019-05-28  2:01 ` Wei Wang
2019-05-28 18:14   ` Eric Hankland
2019-05-29  7:54     ` Wei Wang
2019-05-29 17:11       ` Eric Hankland
2019-05-31  1:02         ` Wei Wang
2019-05-31 19:59           ` Eric Hankland
2019-06-01 10:55             ` Wei Wang
2019-06-03 17:30               ` Eric Hankland
2019-06-04  4:42                 ` Wei Wang
2019-06-04 15:56                   ` Eric Hankland
     [not found]                     ` <CAEU=KTHsVmrAHXUKdHu_OwcrZoy-hgV7pk4UymtchGE5bGdUGA@mail.gmail.com>
2019-06-05 21:35                       ` Eric Hankland
2019-06-06  7:36                         ` Wei Wang
2019-06-13 17:43                           ` Eric Hankland
2019-06-14  9:14                             ` Wei Wang
2019-06-14  9:26 ` Wei Wang
2019-06-25  0:32   ` Eric Hankland
2019-06-25  9:12     ` Wei Wang
2019-07-02 17:46       ` Eric Hankland
2019-07-03  9:06         ` Wei Wang
2019-06-20 18:05 ` Andi Kleen [this message]
2019-06-24 23:56   ` Eric Hankland

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