Messages in this thread | | | From | Bryan Donlan <> | Date | Sun, 4 Oct 2009 21:44:13 -0400 | Subject | Re: [PATCH] Added PR_SET_PROCTITLE_AREA option for prctl() |
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On Sun, Oct 4, 2009 at 9:38 PM, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: >> The improvement idea is here. >> >> Changelog >> - Added task_lock() to prctl(PR_SET_PROCTITLE_AREA) >> - Added small input sanity check to prctl(PR_SET_PROCTITLE_AREA) > > Doh, task_lock() is obviously wrong. please forget this.
As another note, in general I think we'd need to hold a lock over the entire operation. After all, if userspace changes its PROCTITLE_AREA, and then reuses the memory for something else, we have an information leak.
Perhaps a simpler approach would simply be to add a generation counter. Read it once at the start, barrier, then grab the title. Then at the end, read the generation counter again. If the value changed, we need to start over. Also, in this case, an error when reading the target process' memory should be ignored and retried, as we may have hit a race in which the target process unmapped the proctitle area after changing it. -- 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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