Date: Mon, 1 Aug 2011 23:22:45 +0400 From: Vasiliy Kulikov <segoon@...nwall.com> To: kernel-hardening@...ts.openwall.com Cc: Ingo Molnar <mingo@...e.hu>, "Paul E. McKenney" <paul.mckenney@...aro.org>, Manuel Lauss <manuel.lauss@...glemail.com>, linux-kernel@...r.kernel.org, Richard Weinberger <richard@....at>, torvalds@...ux-foundation.org, Marc Zyngier <maz@...terjones.org> Subject: Re: Re: initcall dependency problem (ns vs. threads) On Mon, Aug 01, 2011 at 12:07 -0700, Andrew Morton wrote: > On Mon, 1 Aug 2011 23:03:41 +0400 > Vasiliy Kulikov <segoon@...nwall.com> wrote: > > > > Are we talking about init_ipc_ns.ids here? If so, did you try > > > initializing the three rwsems at compile-time? > > > > > > That's rather a nasty hack though. It'd be better to run the mystery > > > init function before starting the threads. > > > > Looks like it solves the race. > > What patch are you talking about here? Sorry for short sentences :) I tried the patch you've suggested - initialize rw_mutex in the init_ipc_ns declaration. Surely, it solves a specific race. As no kernel threads actually use shm, other fields are not needed to be initialized before do_initcall(). However, it is a bit ugly as it divides namespace initialization code into init_ipc_ns initialization and other namespaces. It's better to use the same code for all namespaces (as it currently is). > > However, I think it should be solved on > > another level. > > What level? I mean it is a bug of _implicit_ assume that kthreads don't use ns related information. So, AFAICS, it can be fixed 2 ways: 1) Move creations of kernel threads somewhere after namespaces initializations in the init chain. 2) Deferring threads creation until all ns initialization is done. > > Other bugs might be hidden with this race. > > What bugs? I don't speak about specific bugs (I know the only one, which is this shm related bug), but I suppose some threads might use some ns related information as well. At least I don't see whether it is somehow explicitly denied currently. Thanks, -- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.