Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: can we make anonymous memory non-EXECUTABLE? | Date | 8 Jan 2002 18:44:55 -0800 |
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Followup to: <15419.17581.990574.160248@napali.hpl.hp.com> By author: David Mosberger <davidm@napali.hpl.hp.com> In newsgroup: linux.dev.kernel > > I don't consider SIGSEGV to be a silent failure. Also, I think > all the evidence is that it's unlikely to break many existing > apps: > > o The bug I described has been present for *years* on > Alpha and probably all other platforms other than x86; > even on ia64 it took almost two years before someone > noticed. It's possible that nobody noticed because > the code generators were part of a larger program, > but it's very likely that anyone writing a test program > would have allocated the non-executable memory, so you'd > expect *someone* to have run into it at some point. > > o Certain libraries such as the Boehm Garbage Collector > already turn off execute permission by default. While > there may not be that many apps that use it in a production > environment, it is my impression that many developers are > using it as a memory-leak detector (e.g., Mozilla does that). > > > DaveM> Secondly, I do not see any > DaveM> real gain from any of this and my ports are those that have > DaveM> I-cache coherency issues :-) > > I think that's fine. If the consensus is that apps *should* use > mprotect() to get executable permission (Linus implied as much) and > it's an architecture specific choice as to whether this is enforced, > I'm happy. My belief is that we could make this change on ia64 > without undue burden on programmers. If not, I'm sure I'll find out > about it and I'm willing to take the responsibility. >
One way to do this would be to create a newbrk() syscall which takes a permission argument (for new pages.)
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