On 28/11/2018 1:52 pm, David Sterba wrote: > The fix is adding a few branches to code that's supposed to be as fast > as possible. The branches would be evaluated all the time while > protecting against one signle bad page address. This does not look like > a good performance tradeoff.
As an alternative, for all but the first case, instead of: if (unlikely(OVERFLOW_ADD_CHECK(ip, m_len) || (ip + m_len >= ip_end))) I'd suggest we do: if (unlikely((ip_end - ip) <= m_len)) which will be about as efficient as what's currently there, but doesn't have issues with overflow. Dave
