From: Julien Grall <julien.grall@linaro.org>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Xen-devel <xen-devel@lists.xen.org>
Cc: Jan Beulich <jbeulich@suse.com>
Subject: Re: [PATCH for-4.10] xen/domctl: Fix Xen heap leak via XEN_DOMCTL_getvcpucontext
Date: Mon, 9 Oct 2017 12:40:51 +0100 [thread overview]
Message-ID: <f6b11151-5cad-3da7-4cf0-d46202cd3fb0@linaro.org> (raw)
In-Reply-To: <1507543638-13706-1-git-send-email-andrew.cooper3@citrix.com>
Hi Andrew,
On 09/10/17 11:07, Andrew Cooper wrote:
> The backing structure for XEN_DOMCTL_getvcpucontext is only zeroed in the x86
> HVM case. At the very least, this means that ARM returns junk through its
> flags field (as it is only ever conditionally or'd into), and x86 PV leaks
> data through gdt_frames[14...15]. (An exhaustive search for other leaks
> hasn't been performed).
>
> Unconditionally zero the memory upon allocation, and forgo the double clear
> for x86 HVM. These hypercalls are not on hotpaths.
>
> Note that this does not qualify for an XSA. Per XSA-77,
> XEN_DOMCTL_getvcpucontext is unsafe for disaggregation, meaning that only the
> control domain can use this hypercall.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
> ---
> CC: Julien Grall <julien.grall@arm.com>
Release-Acked-by: Julien Grall <julien.grall@linaro.org>
Cheers,
--
Julien Grall
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prev parent reply other threads:[~2017-10-09 11:40 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-09 10:07 [PATCH for-4.10] xen/domctl: Fix Xen heap leak via XEN_DOMCTL_getvcpucontext Andrew Cooper
2017-10-09 11:40 ` Julien Grall [this message]
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