linux-kernel - RE: bug in sscanf()?

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Message-ID: <804857E1F29AAC47BF68C404FC60A18465432C9C@ORSMSX105.amr.corp.intel.com>
Date:	Tue, 14 Jan 2014 00:32:13 +0000
From:	"Allan, Bruce W" <bruce.w.allan@...el.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Jan Beulich <JBeulich@...e.com>,
	Alexey Dobriyan <adobriyan@...il.com>
Subject: RE: bug in sscanf()?

> -----Original Message-----
> From: linus971@...il.com [mailto:linus971@...il.com] On Behalf Of Linus
> Torvalds
> Sent: Monday, January 13, 2014 4:23 PM
> To: Al Viro
> Cc: Allan, Bruce W; linux-kernel@...r.kernel.org; Jan Beulich; Alexey
> Dobriyan
> Subject: Re: bug in sscanf()?
> 
> On Tue, Jan 14, 2014 at 6:30 AM, Al Viro <viro@...iv.linux.org.uk> wrote:
> >
> > Comments?
> 
> Do we have actual users of this? Because I'd almost be inclined to say
> "we just don't support field widths on sscanf() and will warn" unless
> there are users.
> 
> We've done that before. The kernel has various limited functions. See
> the whole snprint() issue with %n, which we decided that supporting
> the full semantics was actually a big mistake and we actively
> *removed* code that had been misguidedly added just because people
> thought we should do everything a standard user library does..
> 
> Limiting our problem space is a *good* thing, not a bad thing.
> 
> If it's possible, of course, and we don't have nasty users.
> 
>            Linus

I was hoping to use sscanf() in this way for a driver I'm working on to support
Thunderbolt device authentication, but if it's too much to ask for I could probably
work around this.

Bruce.