From: "George Spelvin" <linux@horizon.com>
To: JBeulich@suse.com, joe@perches.com, keescook@chromium.org
Cc: akpm@linux-foundation.org, dan.carpenter@oracle.com,
davem@davemloft.net, eldad@fogrefinery.com,
linux-kernel@vger.kernel.org, linux@horizon.com,
rdunlap@infradead.org
Subject: Re: [PATCH] vsprintf: drop comment claiming %n is ignored
Date: 13 Sep 2013 15:49:15 -0400 [thread overview]
Message-ID: <20130913194915.13780.qmail@science.horizon.com> (raw)
In-Reply-To: <5231836102000078000F29AD@nat28.tlf.novell.com>
> Why would you want to artificially make the function diverge
> from the spec?
Because %n make it easy to convert a not-uncommon format string bug into
a code injection. Thus, poses a significant security vulnerability.
Since it's an obscure and rarely-used feature, it is straightforward
to eliminate all users in the Linux kernel, making removing it possible.
I agree that if it were harmless, it would be useful to leave it
implemented just for simplicity (it's a trivial amount of code), but
it's not harmless.
> People shouldn't be caught by surprises if at all
> possible, and one can certainly not expect people to go look at
> the comment before the function implementation to find out
> what basic (standard) features _do not_ work (one can expect
> so when trying to find out about _extensions_).
This is why people propose implementing it as a kernel warning.
Strongly support this change.
prev parent reply other threads:[~2013-09-13 19:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-11 19:30 Kees Cook
2013-09-11 20:06 ` Joe Perches
2013-09-11 20:18 ` Kees Cook
2013-09-11 20:20 ` Joe Perches
2013-09-11 20:30 ` KOSAKI Motohiro
2013-09-11 20:28 ` Joe Perches
2013-09-13 19:53 ` George Spelvin
2013-09-13 22:27 ` Joe Perches
2013-09-13 23:03 ` Kees Cook
2013-09-13 23:23 ` Joe Perches
2013-09-16 2:53 ` George Spelvin
2013-09-14 2:17 ` Al Viro
2013-09-14 2:49 ` Tetsuo Handa
2013-09-14 3:05 ` Al Viro
2013-09-14 3:48 ` Al Viro
2013-09-14 4:53 ` Al Viro
2013-09-14 5:26 ` Joe Perches
2013-09-12 7:03 ` Jan Beulich
2013-09-12 7:31 ` Kees Cook
2013-09-12 7:51 ` Jan Beulich
2013-09-12 7:57 ` Dan Carpenter
2013-09-13 19:49 ` George Spelvin [this message]
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