Re: [PATCH v2] lzo: fix ip overrun during compress.

Yueyi Li
2018-11-30T03:05:43Z

Hi Dave,

On 2018/11/30 0:49, Dave Rodgman wrote:
> 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.

Ooh, yes, pretty good solution to this, thanks.

> Dave

Thanks,
Yueyi