Re: [PATCH] perf: add sanity check on addr in symbol__inc_addr_samples()

[Stephane Eranian]

On Fri, Feb 10, 2012 at 2:46 PM, Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> 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@xxxxxxxxxx> 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:
>> >> Â Â Â 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:
>
> Â Â Â ÂBUG_ON(addr >= sym->end || addr < sym->start)
>
Fine with me. It makes more sense.

> - Arnaldo
>
>> > - Arnaldo
>> >
>> >> Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
>> >>
>> >> 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,
>> >>
>> >> Â Â Â pr_debug3("%s: addr=%#" PRIx64 "\n", __func__, map->unmap_ip(map, addr));
>> >>
>> >> - Â Â if (addr >= sym->end)
>> >> + Â Â if (addr >= sym->end || addr < sym->start)
>> >> Â Â Â Â Â Â Â return 0;
>> >>
>> >> Â Â Â offset = addr - sym->start;
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/