linux-kernel - Re: [PATCH 1/3] perf script python: Fix string vs byte array resolving

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Date:	Fri, 15 Jul 2016 13:16:53 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Jiri Pirko <jiri@...lanox.com>, Jiri Olsa <jolsa@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 1/3] perf script python: Fix string vs byte array
 resolving

On Fri, 15 Jul 2016 18:13:10 +0200
Jiri Olsa <jolsa@...hat.com> wrote:

> On Fri, Jul 15, 2016 at 12:02:31PM -0400, Steven Rostedt wrote:
> 
> SNIP
> 
> > > for "AA\1\0" this returns "1" although that should return "0".
> > > 
> > > orig len 4
> > > decremented len 3
> > > for:
> > > 0 1
> > > 
> > > index 2 would not be inspected. Or am I missing something?
> > > 
> > > I think that the for check should be "i < len"  
> > 
> > Yes it should be. I think we got the two solutions mixed up.
> > 
> > With the above len--, it should be i < len, but when we did the check
> > for zero at the end, we needed the i < len - 1  
> 
> ugh right.. should be 'i < len' check in the for loop,
> 
> there's also the patch 2/3 that needs to be changed
> 

I'm wondering if we should also add at the beginning:

	if (!len)
		return 0;

Otherwise we will be accessing out of bounds with the len-1.

-- Steve