Messages in this thread | | | Date | Fri, 04 May 2001 10:18:47 -0500 | From | Todd Inglett <> | Subject | Re: SMP races in proc with thread_struct |
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Andreas Ferber wrote: > > On Fri, May 04, 2001 at 10:46:43PM +1000, Keith Owens wrote: > > > For a read only case, the only important > > thing is not to die, one occurrence of bad data is tolerable. > > Strong NACK. The pages where the bad data comes from may in some cases > already be reclaimed for other data, probably something security > relevant, which should never ever be given even read access by an > unauthorized user. Even if this event may be a very rare case, one > single occurrence of this is one to much.
Agreed. Worse, it is not readonly. The /proc code task_lock's the task struct, thus writing to it.
I'll post a patch shortly once I've tested it. Worse case only if the task is exiting I sweep the tasklist looking for the parent to see if the parent is still valid. I am not verifying if it is the actual parent (it might be a new task allocated at the same spot). I could just report 0 (or 1) for the parent for any process that is exiting, but then you won't be able to see the ppid for zombies. Or is there another state I can look for? What I really need is PF_EXITED :).
I am a little concerned also about mm, file, tty and sig fields. These appear to be NULLed in do_exit(), but I haven't tracked down tty and sig yet. -- -todd - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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