Em Thu, Jun 23, 2016 at 09:07:04AM -0300, Arnaldo Carvalho de Melo escreveu:
> 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.
Tested, reproduced, ammended, fixed, applied, thanks!
- Arnaldo
> - 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;
> >
