On 10/01/2015 03:48 PM, Linus Torvalds wrote: > On Thu, Oct 1, 2015 at 6:33 PM, Dave Hansen <dave@xxxxxxxx> wrote: >> >> Here it is in a quite fugly form (well, it's not opt-in). Init crashes >> if I boot with this, though. >> >> I'll see if I can turn it in to a bit more of an opt-in and see what's >> actually going wrong. ... > That said, I don't understand your patch. Why check PROT_WRITE? We've > had :"execute but not write" forever. It's "execute and not *read*" > that is interesting. I was thinking that almost anybody doing a PROT_WRITE|PROT_EXEC really *is* going to write to it so they'll notice pretty fast if we completely deny them access to it. Also, a quick ftrace showed that most mmap() callers that set PROT_EXEC also set PROT_READ. I'm just assuming that folks are setting PROT_READ but aren't _really_ going to read it, so we can safely deny them all access other than exec. -- 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>