Messages in this thread | | | Date | Fri, 23 Mar 2012 00:46:27 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] futex: do not leak robust list to unprivileged process |
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On Tue, 20 Mar 2012, Ingo Molnar wrote: > * Kees Cook <keescook@chromium.org> wrote: > > On Tue, Mar 20, 2012 at 10:02 AM, Thomas Gleixner <tglx@linutronix.de> wrote: > > > I really wonder why we have this syscall at all. > > > > The documentation I found yesterday while looking at this was: > > http://linux.die.net/man/2/get_robust_list > > > > Which says "The system call is only available for debugging > > purposes and is not needed for normal operations. Both system > > calls are not available to application programs as functions; > > they can be called using the syscall(3) function." > > > > Dropping the syscall entirely would certainly make it secure. > > ;) > > The thinking was API completeness. In general it's possible for > a sufficiently privileged task to figure out all the state of a > task. We can query timers, fds - the robust list is such a > resource as well. The information leakage was obviously not > intended.
So I think it's safe to take Kees' patch as is. On top of that we should add a WARN_ONCE when the syscall is invoked and schedule the sucker for removal.
Thoughts ?
tglx
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