Messages in this thread | | | Date | Tue, 17 Apr 2012 18:47:04 +0800 | From | Jason Wang <> | Subject | Re: [PATCH 5/6] vhost_net: fix use after free of vq->ubufs |
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On 04/17/2012 06:22 PM, Michael S. Tsirkin wrote: > On Tue, Apr 17, 2012 at 11:19:42AM +0800, Jason Wang wrote: >> > On 04/16/2012 09:28 PM, Michael S. Tsirkin wrote: >>> > >On Mon, Apr 16, 2012 at 02:08:25PM +0800, Jason Wang wrote: >>>> > >>When zerocopy socket is used, ubufs pointer were used in handle_tx() >>>> > >>without any validation. This would cause NULL pointer deference after >>>> > >>it has been freed in vhost_net_set_backend(). Fix this by check the >>>> > >>pointer before using it. >>>> > >> >>>> > >>Signed-off-by: Jason Wang<jasowang@redhat.com> >>> > > >>> > >OK so it's NULL dereference and not user after free:) >>> > >Also could you clarify how does this happen pls? >>> > >Don't we always initialize ubufs when vhost_sock_zcopy is set? >> > >> > The problem happens when we want to disable backend. At this time >> > ubufs were assigned to NULL and it may be dereferenced by >> > handle_tx(): > Heh, I see. How about > - zcopy = vhost_sock_zcopy(sock); > + zcopy = vq->ubufs;
Yes, It's more is simpler.
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