linux-kernel - Re: [PATCH] perf: add sanity check on addr in symbol__inc_addr

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Message-ID: <20120210134646.GB4998@infradead.org>
Date:	Fri, 10 Feb 2012 11:46:46 -0200
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu
Subject: Re: [PATCH] perf: add sanity check on addr in
	symbol__inc_addr_samples()

Em Thu, Feb 09, 2012 at 03:53:14PM +0100, Stephane Eranian escreveu:
> On Thu, Feb 9, 2012 at 3:48 PM, Arnaldo Carvalho de Melo
> <acme@...hat.com> wrote:
> > Em Thu, Feb 09, 2012 at 11:30:16AM +0100, Stephane Eranian escreveu:
> >>
> >> Check the value of addr against the bounds of the symbol.
> >> This is needed given we compute an offset:
> >>       offset = addr - sym->start
> >>
> >> And we don't want the offset to become negative.
> >
> > I'll try and add a debug option to show the backtrace and values of
> > addr, sym, etc, so that we can fix the real problem.

> > I.e. this function shouldn't be receiving any such invalid addresses, as
> > the symbol lookup was done, the symbol was found to be this one, then
> > why it would be out of bounds at this point?!

> I tend to agree with you on this. But then I don't see why the first test
> was there.

Its wrong as well, we should leave it there, together with the new test,
but as:

	BUG_ON(addr >= sym->end || addr < sym->start)

- Arnaldo
 
> > - Arnaldo
> >
> >> Signed-off-by: Stephane Eranian <eranian@...gle.com>
> >>
> >> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
> >> index 011ed26..8248d80 100644
> >> --- a/tools/perf/util/annotate.c
> >> +++ b/tools/perf/util/annotate.c
> >> @@ -64,7 +64,7 @@ int symbol__inc_addr_samples(struct symbol *sym, struct map *map,
> >>
> >>       pr_debug3("%s: addr=%#" PRIx64 "\n", __func__, map->unmap_ip(map, addr));
> >>
> >> -     if (addr >= sym->end)
> >> +     if (addr >= sym->end || addr < sym->start)
> >>               return 0;
> >>
> >>       offset = addr - sym->start;
--
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