Messages in this thread | | | Date | Thu, 23 Jun 2016 09:07:04 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found |
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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 <hekuang@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; >
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