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Date: Mon, 9 Nov 2009 19:00:17 -0500 From: Bryan Donlan <bdonlan@...il.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>, Americo Wang <xiyou.wangcong@...il.com>, Timo Sirainen <tss@....fi>, Ulrich Drepper <drepper@...hat.com>, LKML <linux-kernel@...r.kernel.org>, linux-api@...r.kernel.org Subject: Re: [PATCH v5] Added PR_SET_PROCTITLE_AREA option for prctl() On Mon, Nov 9, 2009 at 5:47 PM, Andrew Morton <akpm@...ux-foundation.org> wrote: > What happens if userspace unmaps the memory after telling the kernel to > use it? > > Will processes which try to read the command line get an error reading > /proc? If so, do all the commandline-reading programs in the world > handle this in an appropriate fashion? This case can already occur in the current code; the userspace process would have to munmap() the top of its stack, but it certainly can do so if it tries. In any case, access_process_vm() then returns 0 because of the fault, and thus /proc/pid/cmdline is seen to have zero length. Since a zero-length /proc/pid/cmdline occurs with kernel threads as well, we know this isn't a problem. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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