Em Thu, Jun 23, 2016 at 10:02:39AM +0800, Wangnan (F) escreveu:
> Hi,
>
> This patch fixes a real crash problem when we do 'perf report'
> on an arm64 platform with arm32 program.
> It is introduced by commit f9b2bdf228 ("perf tools: Find vdso
> with the consider of cross-platform"). From dmesg report, perf
> crashes in dso__type() because dso is NULL.
Ok, I removed f9b2bdf228 because of this crash, Ingo reported it, now
that I see this new patch and checked that the crash was introduced by
f9b2bdf228 I'll just combine those two and test again using a 32-bit
hackbench on top of f9b2bdf228, to reproduce the crash, then on top of
both patches combined.
- Arnaldo
> Still don't know why on x86 it never crash, but it is obviously
> that we need to check the return vaule from __dso__find(): it can
> be NULL.
>
> So please consider pulling.
>
> Thank you.
>
> On 2016/6/22 14:57, He Kuang wrote:
> > We should check if 'dso' is a null pointer before passing it to the
> > function dso__type(), otherwise a segfault will be raised in
> > dso__data_get_fd(). In function machine__find_vdso(), the return value
> > checking of 'dso' is missed and this patch fixes this issue.
> >
> > Signed-off-by: He Kuang <heku...@huawei.com>
> > ---
> > tools/perf/util/vdso.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
> > index 8f81c41..7bdcad4 100644
> > --- a/tools/perf/util/vdso.c
> > +++ b/tools/perf/util/vdso.c
> > @@ -296,7 +296,7 @@ static struct dso *machine__find_vdso(struct machine
> > *machine,
> > if (!dso) {
> > dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
> > true);
> > - if (dso_type != dso__type(dso, machine))
> > + if (dso && dso_type != dso__type(dso, machine))
> > dso = NULL;
> > }
> > break;
>
