From: Stefan Hajnoczi <stefanha@redhat.com>
To: Li Qiang <liq3ea@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
Qemu Developers <qemu-devel@nongnu.org>,
Max Reitz <mreitz@redhat.com>, Alexander Bulekov <alxndr@bu.edu>,
"Gonglei \(Arei\)" <arei.gonglei@huawei.com>
Subject: Re: [PATCH 3/3] virtio-crypto: don't modify elem->in/out_sg
Date: Wed, 16 Sep 2020 11:12:07 +0100 [thread overview]
Message-ID: <20200916101207.GB756046@stefanha-x1.localdomain> (raw)
In-Reply-To: <CAKXe6SKE+Zmyethcb6KUWxnr6FpieWe=o3O-cupyxreQObVLWA@mail.gmail.com>
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On Sun, Aug 16, 2020 at 04:32:06PM +0800, Li Qiang wrote:
> Stefan Hajnoczi <stefanha@redhat.com> 于2020年8月12日周三 下午6:51写道：
>
> > A number of iov_discard_front/back() operations are made by
> > virtio-crypto. The elem->in/out_sg iovec arrays are modified by these
> > operations, resulting virtqueue_unmap_sg() calls on different addresses
> > than were originally mapped.
> >
> > This is problematic because dirty memory may not be logged correctly,
> > MemoryRegion refcounts may be leaked, and the non-RAM bounce buffer can
> > be leaked.
> >
> > Take a copy of the elem->in/out_sg arrays so that the originals are
> > preserved. The iov_discard_undo() API could be used instead (with better
> > performance) but requires careful auditing of the code, so do the simple
> > thing instead.
> >
> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> >
>
> virtio-net also uses this method.
virtio-net operates on a copy of the iovecs (g_memdup()) so no changes
are necessary.
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prev parent reply other threads:[~2020-09-16 10:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-12 10:49 [PATCH 0/3] virtio: restore elem->in/out_sg after iov_discard_front/back() Stefan Hajnoczi
2020-08-12 10:49 ` [PATCH 1/3] util/iov: add iov_discard_undo() Stefan Hajnoczi
2020-08-16 8:26 ` Li Qiang
2020-09-16 10:09 ` Stefan Hajnoczi
2020-09-16 15:36 ` Li Qiang
2020-08-12 10:49 ` [PATCH 2/3] virtio-blk: undo destructive iov_discard_*() operations Stefan Hajnoczi
2020-09-16 15:38 ` Li Qiang
2020-09-17 9:34 ` Stefan Hajnoczi
2020-08-12 10:49 ` [PATCH 3/3] virtio-crypto: don't modify elem->in/out_sg Stefan Hajnoczi
2020-08-16 8:32 ` Li Qiang
2020-09-16 10:12 ` Stefan Hajnoczi [this message]
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