From: Juergen Gross <jgross@suse.com>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: boris.ostrovsky@oracle.com, xen-devel@lists.xenproject.org,
linux-kernel@vger.kernel.org, jbeulich@suse.com,
Stefano Stabellini <stefano.stabellini@xilinx.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v4] xen: detect uninitialized xenbus in xenbus_init
Date: Wed, 24 Nov 2021 06:11:40 +0100 [thread overview]
Message-ID: <b7e7ea7f-f08a-61b4-8980-757470d50b55@suse.com> (raw)
In-Reply-To: <20211123210748.1910236-1-sstabellini@kernel.org>
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On 23.11.21 22:07, Stefano Stabellini wrote:
> From: Stefano Stabellini <stefano.stabellini@xilinx.com>
>
> If the xenstore page hasn't been allocated properly, reading the value
> of the related hvm_param (HVM_PARAM_STORE_PFN) won't actually return
> error. Instead, it will succeed and return zero. Instead of attempting
> to xen_remap a bad guest physical address, detect this condition and
> return early.
>
> Note that although a guest physical address of zero for
> HVM_PARAM_STORE_PFN is theoretically possible, it is not a good choice
> and zero has never been validly used in that capacity.
>
> Also recognize all bits set as an invalid value.
>
> For 32-bit Linux, any pfn above ULONG_MAX would get truncated. Pfns
> above ULONG_MAX should never be passed by the Xen tools to HVM guests
> anyway, so check for this condition and return early.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Juergen
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next prev parent reply other threads:[~2021-11-24 5:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 21:07 [PATCH v4] xen: detect uninitialized xenbus in xenbus_init Stefano Stabellini
2021-11-24 5:11 ` Juergen Gross [this message]
2021-11-24 7:33 ` Jan Beulich
2021-11-25 15:20 ` Boris Ostrovsky
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