Date: Wed, 28 Mar 2012 23:24:07 +0200 (CEST) From: Thomas Gleixner <tglx@...utronix.de> To: Kees Cook <keescook@...omium.org> cc: Ingo Molnar <mingo@...nel.org>, Serge Hallyn <serge.hallyn@...onical.com>, LKML <linux-kernel@...r.kernel.org>, Darren Hart <dvhart@...ux.intel.com>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Andrew Morton <akpm@...ux-foundation.org>, Jiri Kosina <jkosina@...e.cz>, "Eric W. Biederman" <ebiederm@...ssion.com>, David Howells <dhowells@...hat.com>, kernel-hardening@...ts.openwall.com, spender@...ecurity.net Subject: Re: [PATCH] futex: do not leak robust list to unprivileged process On Wed, 28 Mar 2012, Kees Cook wrote: > On Thu, Mar 22, 2012 at 4:46 PM, Thomas Gleixner <tglx@...utronix.de> wrote: > > On Tue, 20 Mar 2012, Ingo Molnar wrote: > >> * Kees Cook <keescook@...omium.org> wrote: > >> > On Tue, Mar 20, 2012 at 10:02 AM, Thomas Gleixner <tglx@...utronix.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. > > Can someone claim the first patch? It looks like not everyone agrees > about removal, but I'd like to see at least the first one get in. :) It's on my list for tomorrow.
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