Messages in this thread | | | Date | Fri, 2 May 2003 11:50:42 -0700 (PDT) | From | Davide Libenzi <> | Subject | Re: [Announcement] "Exec Shield", new Linux security feature |
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On Fri, 2 May 2003, Florian Weimer wrote:
> Davide Libenzi <davidel@xmailserver.org> writes: > > > On Fri, 2 May 2003, Florian Weimer wrote: > > > >> Davide Libenzi <davidel@xmailserver.org> writes: > >> > >> > Ingo, do you want protection against shell code injection ? Have the > >> > kernel to assign random stack addresses to processes and they won't be > >> > able to guess the stack pointer to place the jump. > >> > >> If your software is broken enough to have buffer overflow bugs, it's > >> not entirely unlikely that it leaks the stack address as well (IIRC, > >> BIND 8 did). > > > > Leaking the stack address is not a problem in this case, since the next > > run will be very->very->very likely different. > > Usually, you can't afford a fork() and execve() for each request you > process. 8-(
You just do it once in your main() task and one for each thread. It's not so bad. Only thing is a ( tunable ) waste of stack space.
> (In addition, GCC might optimize away those alloca() calls.)
Luckily enough it doesn't. I checked this a long time ago since I had the same fear due the builtin_alloca.
- Davide
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