linux-kernel - Re: [dpdk-dev] [PATCH 2/2] uio: new driver to support PCI MSI-X

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Message-ID: <5613DF71.7090207@cloudius-systems.com>
Date:	Tue, 6 Oct 2015 17:49:21 +0300
From:	Vlad Zolotarov <vladz@...udius-systems.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	hjk@...sjkoch.de, dev@...k.org, gregkh@...ux-foundation.org,
	Stephen Hemminger <stephen@...workplumber.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [dpdk-dev] [PATCH 2/2] uio: new driver to support PCI MSI-X



On 10/06/15 16:58, Michael S. Tsirkin wrote:
> On Tue, Oct 06, 2015 at 11:23:11AM +0300, Vlad Zolotarov wrote:
>> Michael, how this or any other related patch is related to the problem u r
>> describing?
>> The above ability is there for years and if memory serves me
>> well it was u who wrote uio_pci_generic with this "security flaw".  ;)
> I answered all this already.
>
> This patch enables bus mastering, enables MSI or MSI-X

This may be done from the user space right now without this patch...

> , and requires
> userspace to map the MSI-X table

Hmmm... I must have missed this requirement. Could u, pls., clarify? 
 From what I see, MSI/MSI-X table is configured completely in the kernel 
here...

> and read/write the config space.
> This means that a single userspace bug is enough to corrupt kernel
> memory.

Could u, pls., provide and example of this simple bug? Because it's 
absolutely not obvious...

>
> uio_pci_generic does not enable bus mastering or MSI, and
> it might be a good idea to have uio_pci_generic block
> access to MSI/MSI-X config.

Since device bars may be mapped bypassing the UIO/uio_pci_generic - this 
won't solve any issue.


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