Messages in this thread | | | Date | Mon, 1 Aug 2011 22:34:01 +0400 | From | Vasiliy Kulikov <> | Subject | Re: [kernel-hardening] Re: initcall dependency problem (ns vs. threads) |
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On Mon, Aug 01, 2011 at 11:20 -0700, Andrew Morton wrote: > There's not really enough detail here for me to suggest a fix without > actually doing some work. Which ipc initialization function is being > called to late?
The call sequence is:
static int __init ipc_init(void) { ... shm_init(); ... } __initcall(ipc_init);
void __init shm_init (void) { shm_init_ns(&init_ipc_ns); ...
void shm_init_ns(struct ipc_namespace *ns) { ... ipc_init_ids(&shm_ids(ns));
void ipc_init_ids(struct ipc_ids *ids) { init_rwsem(&ids->rw_mutex); ...
The code triggering the oops (called from do_exit()):
void exit_shm(struct task_struct *task) { ... down_write(&shm_ids(ns).rw_mutex);
> Which thread is using which data structures before > which initialization function has been run?
Actually, it doesn't matter. If ANY thread exits before init_rwsem() then exit_shm() would use uninitialized shm_ids(ns).rw_mutex.
> Are we talking about init_ipc_ns.ids[] here? If so, did you try > initializing the three rwsems at compile-time?
No, good idea. I'll do it.
IMO moving specific initializer is bad by design. There should be a guarantee what resources are accessible on what boot stage. I suppose it should be: all thread related information (including ns data) is accessible for the moment of threads' code execution.
Thanks,
-- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments
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