linux-kernel - [PATCH 0/2] finx argv

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Date:	Sat, 16 Mar 2013 21:23:27 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Lucas De Marchi <lucas.de.marchi@...il.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Paul Mackerras <paulus@...ba.org>, david@...son.dropbear.id.au,
	Kees Cook <keescook@...omium.org>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Feng Hong <hongfeng@...vell.com>,
	Lucas De Marchi <lucas.demarchi@...fusion.mobi>
Subject: [PATCH 0/2] finx argv_split() vs sysctl race

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.

> But, whatever we do with argv_split(), it can hit the string "in between".
> Personally I think we do not really care, but...
>
> Perhaps we should add proc_dostring_lock() which takes some lock and
> modify the callers of argv_split() (or add argv_split_lock) ?
>
> Or perhaps we should introduce the rwsem which should protect every
> sysctl-string and proc_dostring() should take this lock?

Please tell me if you think we should do something with that.

Oleg.

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