linux-kernel - Re: [PATCH] lib: string.c: Added a funktion function strzcpy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140924154142.GG5865@mwanda>
Date:	Wed, 24 Sep 2014 18:41:42 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Andi Kleen <ak@...ux.intel.com>
Cc:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>,
	Grant Likely <grant.likely@...aro.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib: string.c:  Added a funktion function strzcpy

On Wed, Sep 24, 2014 at 07:35:55AM -0700, Andi Kleen wrote:
> On Wed, Sep 24, 2014 at 10:52:06AM +0300, Dan Carpenter wrote:
> > On Tue, Sep 23, 2014 at 06:17:53PM -0700, Andi Kleen wrote:
> > > On Wed, Sep 24, 2014 at 12:13:36AM +0200, Rickard Strandqvist wrote:
> > > > Added a function strzcpy which works the same as strncpy,
> > > > but guaranteed to produce the trailing null character.
> > > 
> > > Do we really need the bizarre strncpy padding semantics for anything?
> > > Why not just use strlcpy?
> > 
> > We do need the padding in many places to prevent information leaks.
> 
> Like where?
> 

You're asking what would break if we switched every strncpy() to
strlcpy() but it's not an easy question to answer.

I've looked a lot at information leaks, but strings are still a blind
spot for my Smatch.  My check only looks at normal variables, arrays.
Eventually I hope to fix this, of course.

I did a git search and Rickard has added some examples, but there were
definitely other places that rely strncpy() padding before.

regards,
dan carpenter

--
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/