On 03/16, Andi Kleen wrote: > > On Sat, Mar 16, 2013 at 09:23:27PM +0100, Oleg Nesterov wrote: > > On 03/15, Oleg Nesterov wrote: > > > > > > To remind, say, argv_split(poweroff_cmd) can race with sysctl changing > > > this > > > string, in this case it can write to the memory after argv[] array. We can > > > fix this, or we can rewrite argv_split/free: > > > > OK, please see 1/2. > > > > And this reminds me about set_task_comm() which pretends it does something > > meaningful for the reader of the mutable ->comm, see the offtopic 2/2. > > I had "rcu strings" to handle the sysctl string race problem in a > generic way some time ago. > > http://lwn.net/Articles/368684/ > > Unfortunately never made it in. Perhaps it should be revisited.
Perhaps rcu can be better, although a global rwsem looks simpler, I dunno. But argv_split() or its usage should be changed anyway, and GFP_KERNEL won't work under rcu_read_lock(). To me 1/2 looks as a simplification anyway, but I won't argue if we decide to add rcu/locking and avoid this patch. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
