From: Jason Gunthorpe <jgg@nvidia.com>
To: Steven Sistare <steven.sistare@oracle.com>
Cc: kvm@vger.kernel.org, Alex Williamson <alex.williamson@redhat.com>,
Cornelia Huck <cohuck@redhat.com>
Subject: Re: [PATCH V4 2/5] vfio/type1: prevent locked_vm underflow
Date: Thu, 15 Dec 2022 11:03:54 -0400 [thread overview]
Message-ID: <Y5s3Wkb5JoPCO1Fs@nvidia.com> (raw)
In-Reply-To: <4736f410-e925-3eb7-7c33-bcf4ad9b55a0@oracle.com>
On Thu, Dec 15, 2022 at 09:38:42AM -0500, Steven Sistare wrote:
> > I'm not sure this is quite, right, or at least the comment isn't quite
> > right..
> >
> > The issue is that the vfio_dma does not store the mm that provided the
> > pages. By going through the task every time it allows the mm to change
> > under its feet which of course can corrupt the assumed accounting in
> > various ways.
> >
> > To fix this, the mm should be kept, as you did above. All the code
> > that is touching the task to get the mm should be dropped. The only
> > purpose of the task is to check the rlimit.
>
> Yes. While developing my "redo" series I tried it that way, but did not post
> that version. Functionally it should be equivalent to this series, but I can
> code it again to see if it looks cleaner.
The big reason to split is that this existing bug pre-dates the vaddr
work and should probably be backported further. It can be triggered
just by doing exec..
Jason
next prev parent reply other threads:[~2022-12-15 15:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-14 21:24 [PATCH V4 0/5] fixes for virtual address update Steve Sistare
2022-12-14 21:24 ` [PATCH V4 1/5] vfio/type1: exclude mdevs from VFIO_UPDATE_VADDR Steve Sistare
2022-12-15 4:34 ` Tian, Kevin
2022-12-15 14:32 ` Steven Sistare
2022-12-14 21:24 ` [PATCH V4 2/5] vfio/type1: prevent locked_vm underflow Steve Sistare
2022-12-15 4:52 ` Tian, Kevin
2022-12-15 14:33 ` Steven Sistare
2022-12-15 14:20 ` Jason Gunthorpe
2022-12-15 14:38 ` Steven Sistare
2022-12-15 15:03 ` Jason Gunthorpe [this message]
2022-12-14 21:24 ` [PATCH V4 3/5] vfio/type1: revert "block on invalid vaddr" Steve Sistare
2022-12-14 21:24 ` [PATCH V4 4/5] vfio/type1: revert "implement notify callback" Steve Sistare
2022-12-14 21:24 ` [PATCH V4 5/5] vfio: revert "iommu driver " Steve Sistare
2022-12-14 21:42 ` [PATCH V4 0/5] fixes for virtual address update Alex Williamson
2022-12-15 14:25 ` Jason Gunthorpe
2022-12-15 18:37 ` Alex Williamson
-- strict thread matches above, loose matches on Subject: below --
2022-12-15 21:53 Steve Sistare
2022-12-15 21:53 ` [PATCH V4 2/5] vfio/type1: prevent locked_vm underflow Steve Sistare
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