Re: [PATCH] Properly handle \0 delimited string lists

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Thu, Jun 12, 2014 at 05:47:28PM -0500, Jack Miller wrote:
> On Wed, Jun 11, 2014 at 11:10:39PM +1000, David Gibson wrote:
> > Hi Jack,
> > 
> > Long time no see :).
> 
> Yeah, I was pretty pleased to have an excuse to send something your way =)
> 
> > 
> > On Tue, Jun 10, 2014 at 02:57:36PM -0500, Jack Miller wrote:
> > > reserved-names="res1\0res2\0res3";
> > > 
> > > Is valid DTS. This one-liner expands data based on the len given by the lexer
> > > instead of strlen.
> > > 
> > > Without this patch, realloc gets confused and hangs. For example:
> > > 
> > > *** Error in `./dtc': realloc(): invalid next size: 0x0000000001961670
> > > ***
> > 
> > So.. the patch certainly isn't wrong, and is arguably safer than the
> > current version.
> > 
> > But.. I haven't been able to reproduce the problem, and I don't really
> > see how it would occur in the first place.
> > 
> > The thing we're taking a strlen of is the input with it's escapes, so
> > it won't have NULs, just backslashes and 0 digits.
> > 
> > Or am I missing something?
> 
> Sorry, I was unclear. The \0 was my short hand for a real embedded NULL
> character, which may be intentionally wrong-headed, but I don't think it's
> invalid (or if it is invalid, should at least not cause the compiler to do
> bad things).

Ah, I see.

Yes, NULs in the input is a bit perverse, but I don't see any reason
it should be invalid.

> In refining my testcase I realized that it doesn't fail on realloc with all
> bad input, but it does generate mangled output otherwise.
> 
> I've uploaded two short .dts snippets just because pasting NULLs into an
> email seems like a bad idea:
> 
> http://codezen.org/static/broken-dts.tar.gz
> 
> One causes the realloc, the other causes the mangled output on git HEAD. Both
> are working properly with my patch.

Ok.  Could you make those into a testcase?

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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