[dpdk-dev] [PATCH v3] eal: fix use-after-free issue on thread creation

[Jianfeng Tan <jianfeng.tan@intel.com>]

After below commit, we encounter some strange issue:
  1) Dead lock as described here:
     http://dpdk.org/ml/archives/dev/2018-April/099806.html
  2) SIGSEGV issue when starting a testpmd in VM.

Considering below commit changes to use dynamic memory instead of
stack for memory barrier, we doubt it's caused by use-after-free.

Fixes: 3d09a6e26d8b ("eal: fix threads block on barrier")

Reported-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reported-by: Lei Yao <lei.a.yao@intel.com>
Suggested-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
Suggested-by: Olivier Matz <olivier.matz@6wind.com>
---
 v1->v2:
 - Destroy barrier if failure happens.
 v2->v3:
 - Add proper failure handling.
 lib/librte_eal/common/eal_common_thread.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
index de69452..cb0855d 100644
--- a/lib/librte_eal/common/eal_common_thread.c
+++ b/lib/librte_eal/common/eal_common_thread.c
@@ -149,11 +149,16 @@ struct rte_thread_ctrl_params {
 
 static void *rte_thread_init(void *arg)
 {
+	int ret;
 	struct rte_thread_ctrl_params *params = arg;
 	void *(*start_routine)(void *) = params->start_routine;
 	void *routine_arg = params->arg;
 
-	pthread_barrier_wait(&params->configured);
+	ret = pthread_barrier_wait(&params->configured);
+	if (ret == PTHREAD_BARRIER_SERIAL_THREAD) {
+		pthread_barrier_destroy(&params->configured);
+		free(params);
+	}
 
 	return start_routine(routine_arg);
 }
@@ -204,14 +209,21 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
 	if (ret < 0)
 		goto fail;
 
-	pthread_barrier_wait(&params->configured);
-	free(params);
+	ret = pthread_barrier_wait(&params->configured);
+	if (ret == PTHREAD_BARRIER_SERIAL_THREAD) {
+		pthread_barrier_destroy(&params->configured);
+		free(params);
+	}
 
 	return 0;
 
 fail:
+	if (PTHREAD_BARRIER_SERIAL_THREAD ==
+	    pthread_barrier_wait(&params->configured)) {
+		pthread_barrier_destroy(&params->configured);
+		free(params);
+	}
 	pthread_cancel(*thread);
 	pthread_join(*thread, NULL);
-	free(params);
 	return ret;
 }
-- 
2.7.4