netdev - Re: [PATCH] [PATCH net v2]vexy: Fix a use-after-free bug in vxge-main.c

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Date:   Mon, 20 Jun 2022 10:40:16 -0400
From:   Jon Mason <jdmason@...zu.us>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Wentao_Liang <Wentao_Liang_g@....com>, davem@...emloft.net,
        edumazet@...gle.com, pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [PATCH net v2]vexy: Fix a use-after-free bug in
 vxge-main.c

On Wed, Jun 15, 2022 at 07:50:50PM -0700, Jakub Kicinski wrote:
> Jon, if you're there, do you have any sense on whether this HW is still
> in production somewhere? I scrolled thru last 5 years of the git history
> and there doesn't seem to be any meaningful change here while there's a
> significant volume of refactoring going in. 

Neterion was killed off by Exar after acquiring it roughly a decade
ago.  To my knowledge no one ever acquired the IP.  So, this should be
viewed as an EOL'ed part.  It is a mature driver and I believe there are
parts out in the field still.  So, no need to kill off the driver.

Thanks,
Jon

> 
> 
> On the patch itself:
> 
> On Wed, 15 Jun 2022 09:38:16 +0800 Wentao_Liang wrote:
> > Subject: [PATCH] [PATCH net v2]vexy: Fix a use-after-free bug in vxge-main.c
> 
> No need to repeat "[PATCH]"
> The driver is not called "vexy" as far as I can tell.
> 
> > The pointer vdev points to a memory region adjacent to a net_device
> > structure ndev, which is a field of hldev. At line 4740, the invocation
> > to vxge_device_unregister unregisters device hldev, and it also releases
> > the memory region pointed by vdev->bar0. At line 4743, the freed memory
> > region is referenced (i.e., iounmap(vdev->bar0)), resulting in a
> > use-after-free vulnerability. We can fix the bug by calling iounmap
> > before vxge_device_unregister.
> 
> Are you sure the bar0 is not needed by the netdev? You're freeing
> memory that the netdev may need until it's unregistered.