On Tue 27-06-17 15:07:17, Kees Cook wrote: > On Tue, Jun 27, 2017 at 12:31 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > But I am not really sure I understand consequences of this patch. So how > > do those attacks look like. Do you have an example of a CVE which would > > be prevented by this measure? > > It's a regular practice, especially for heap grooming. You can see an > example here: > http://cyseclabs.com/blog/cve-2016-6187-heap-off-by-one-exploit > which even recognizes this as a common method, saying "the standard > msgget() technique". Having the separate caches doesn't strictly > _stop_ some attacks, but it changes the nature of what the attacker > has to do. Instead of having a universal way to groom the heap, they > must be forced into other paths. Generally speaking this can reduce > what's possible making the attack either impossible, more expensive to > develop, or less reliable. Thanks that makes it more clear to me. I believe this would be a useful information in the changelog. > >> This would mean building out *_user() versions for all the various > >> *alloc() functions, though. That gets kind of long/ugly. > > > > Only prepare those which are really needed. It seems only handful of > > them in your patch. > > Okay, if that's the desired approach, we can do that. yes please -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
