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.

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;


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