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

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Message-ID: <CABPqkBSuSmnGB2J53kvwJYcUndC5RRC76w_kzZjSCX49n_iyFg@mail.gmail.com>
Date:	Fri, 10 Feb 2012 14:49:17 +0100
From:	Stephane Eranian <eranian@...gle.com>
To:	Arnaldo Carvalho de Melo <acme@...hat.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()

On Fri, Feb 10, 2012 at 2:46 PM, Arnaldo Carvalho de Melo
<acme@...hat.com> wrote:
> 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)
>
Fine with me. It makes more sense.

> - 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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