Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Sun, 17 Jan 2016 09:59:52 +0100
From: Jens Gustedt <>
Subject: Re: Non-stub setvbuf

Am Samstag, den 16.01.2016, 20:43 -0500 schrieb Rich Felker:
> Right now, musl's stdio setvbuf function does nothing but set the
> buffering mode; it does not honor the buffer provided by the caller.
> This is perfectly conforming (whether or how the buffer is used is
> unspecified), but I realized from the recent thread about OpenSSH's
> CVE-2016-0777 on oss-security that a non-stub setvbuf admits a nice
> type of hardening:
> In short, the application has no way to scrub implementation-internal
> stdio buffers that might contain sensitive data read from or written
> to files, but it can scrub buffers it provides via setvbuf. So, I'd
> like to start actually using the latter, so that apps that attempt
> this hardening measure can benefit from it on musl like they would on
> other implementations.

How about just using setvbuf as an indication that the user wants the
buffer to be scrubbed? And so just zero it?

I wouldn't expect setvbuf to be used in places that are performance
critical, so an additional memset shouldn't do much harm, I think.


:: INRIA Nancy Grand Est ::: Camus ::::::: ICube/ICPS :::
:: ::::::::::::::: office Strasbourg : +33 368854536   ::
:: :::::::::::::::::::::: gsm France : +33 651400183   ::
:: ::::::::::::::: gsm international : +49 15737185122 ::
:: ::

Download attachment "signature.asc" of type "application/pgp-signature" (182 bytes)

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.