On Thu, Jun 29, 2017 at 10:56 AM, Tycho Andersen <tycho@xxxxxxxxxx> wrote: > On Thu, Jun 29, 2017 at 01:54:13PM -0400, Rik van Riel wrote: >> On Thu, 2017-06-29 at 10:47 -0700, Kees Cook wrote: >> > On Thu, Jun 29, 2017 at 10:05 AM, Christoph Lameter <cl@xxxxxxxxx> >> > wrote: >> > > On Sun, 25 Jun 2017, Kees Cook wrote: >> > > >> > > > The difference gets lost in the noise, but if the above is >> > > > sensible, >> > > > it's 0.07% slower. ;) >> > > >> > > Hmmm... These differences add up. Also in a repetative benchmark >> > > like that >> > > you do not see the impact that the additional cacheline use in the >> > > cpu >> > > cache has on larger workloads. Those may be pushed over the edge of >> > > l1 or >> > > l2 capacity at some point which then causes drastic regressions. >> > >> > Even if that is true, it may be worth it to some people to have the >> > protection. Given that is significantly hampers a large class of heap >> > overflow attacks[1], I think it's an important change to have. I'm >> > not >> > suggesting this be on by default, it's cleanly behind >> > CONFIG-controlled macros, and is very limited in scope. If you can >> > Ack >> > it we can let system builders decide if they want to risk a possible >> > performance hit. I'm pretty sure most distros would like to have this >> > protection. >> >> I could certainly see it being useful for all kinds of portable >> and network-connected systems where security is simply much >> more important than performance. > > Indeed, I believe we would enable this in our kernels. Andrew and Christoph, What do you think about carrying this for -mm, since people are interested in it and it's a very narrow change behind a config (with a large impact on reducing the expoitability of freelist pointer overwrites)? -Kees -- Kees Cook Pixel Security -- 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>
