[PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found

From: He Kuang <hekuang@huawei.com>
To: <peterz@infradead.org>, <mingo@redhat.com>, <acme@kernel.org>,
	<alexander.shishkin@linux.intel.com>, <jolsa@redhat.com>,
	<wangnan0@huawei.com>, <hekuang@huawei.com>,
	<jpoimboe@redhat.com>, <ak@linux.intel.com>, <eranian@google.com>,
	<namhyung@kernel.org>, <adrian.hunter@intel.com>,
	<sukadev@linux.vnet.ibm.com>, <masami.hiramatsu.pt@hitachi.com>,
	<tumanova@linux.vnet.ibm.com>, <kan.liang@intel.com>,
	<penberg@kernel.org>, <dsahern@gmail.com>
Cc: <linux-kernel@vger.kernel.org>
Subject: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found
Date: Wed, 22 Jun 2016 06:57:06 +0000	[thread overview]
Message-ID: <1466578626-92406-6-git-send-email-hekuang@huawei.com> (raw)
In-Reply-To: <1466578626-92406-1-git-send-email-hekuang@huawei.com>

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;
-- 
1.8.5.2
