From: Paolo Bonzini <pbonzini@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Radim Krčmář" <rkrcmar@redhat.com>,
"Wanpeng Li" <wanpeng.li@hotmail.com>,
Moguofang <moguofang@huawei.com>
Subject: Re: [PATCH] KVM: X86: Fix read out-of-bounds vulnerability in kvm pio emulation
Date: Fri, 19 May 2017 12:33:13 +0200 [thread overview]
Message-ID: <d3dc4ca8-0000-4cf6-b2b0-06bee400a8dd@redhat.com> (raw)
In-Reply-To: <1495187216-9294-1-git-send-email-wanpeng.li@hotmail.com>
On 19/05/2017 11:46, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
>
> Huawei folks reported a read out-of-bounds vulnerability in kvm pio emulation.
>
> - "inb" instruction to access PIT Mod/Command register (ioport 0x43, write only,
> a read should be ignored) in guest can get a random number.
> - "rep insb" instruction to access PIT register port 0x43 can control memcpy()
> in emulator_pio_in_emulated() to copy max 0x400 bytes but only read 1 bytes,
> which will disclose the unimportant kernel memory in host but no crash.
The data comes simply from the last PIO read, right? The vcpu struct is
zero-initialized, so there is no kernel memory leak---the byte was
already previously known to the guest.
Good catch though, and the patch looks good.
Thanks,
Paolo
> The similar test program below can reproduce the read out-of-bounds vulnerability:
prev parent reply other threads:[~2017-05-19 10:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-19 9:46 Wanpeng Li
2017-05-19 10:33 ` Paolo Bonzini [this message]
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