On Wed, Sep 23, 2015 at 7:43 PM, Pravin Shelar <pshe...@nicira.com> wrote:
> On Tue, Sep 22, 2015 at 6:17 PM, Jesse Gross <je...@nicira.com> wrote:
>> Upstream commit:
>> openvswitch: Zero flows on allocation.
>>
>> When support for megaflows was introduced, OVS needed to start
>> installing flows with a mask applied to them. Since masking is an
>> expensive operation, OVS also had an optimization that would only
>> take the parts of the flow keys that were covered by a non-zero
>> mask. The values stored in the remaining pieces should not matter
>> because they are masked out.
>>
>> While this works fine for the purposes of matching (which must always
>> look at the mask), serialization to netlink can be problematic. Since
>> the flow and the mask are serialized separately, the uninitialized
>> portions of the flow can be encoded with whatever values happen to be
>> present.
>>
>> In terms of functionality, this has little effect since these fields
>> will be masked out by definition. However, it leaks kernel memory to
>> userspace, which is a potential security vulnerability. It is also
>> possible that other code paths could look at the masked key and get
>> uninitialized data, although this does not currently appear to be an
>> issue in practice.
>>
>> This removes the mask optimization for flows that are being installed.
>> This was always intended to be the case as the mask optimizations were
>> really targetting per-packet flow operations.
>>
>> Fixes: 03f0d916 ("openvswitch: Mega flow implementation")
>> Signed-off-by: Jesse Gross <je...@nicira.com>
>> Acked-by: Pravin B Shelar <pshe...@nicira.com>
>> Signed-off-by: David S. Miller <da...@davemloft.net>
>>
>> Upstream: ae5f2fb1 ("openvswitch: Zero flows on allocation.")
>> Signed-off-by: Jesse Gross <je...@nicira.com>
>
> Acked-by: Pravin B Shelar <pshe...@nicira.com>
Thanks, applied to master, branch-2.4 and branch-2.3.
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