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* [dpdk-stable] [PATCH 19.11.9 1/2] eal: fix race in control thread creation
@ 2021-05-21 15:49 Luc Pelletier
  2021-05-21 15:49 ` [dpdk-stable] [PATCH 19.11.9 2/2] eal: fix hang " Luc Pelletier
  2021-06-03  4:59 ` [dpdk-stable] [PATCH 19.11.9 1/2] eal: fix race " Christian Ehrhardt
  0 siblings, 2 replies; 4+ messages in thread
From: Luc Pelletier @ 2021-05-21 15:49 UTC (permalink / raw)
  To: christian.ehrhardt, stable; +Cc: Luc Pelletier

[ upstream commit 34cc55cce6b180a6c3ee3fcf70a0fd56927f240d ]

The creation of control threads uses a pthread barrier for
synchronization. This patch fixes a race condition where the pthread
barrier could get destroyed while one of the threads has not yet
returned from the pthread_barrier_wait function, which could result in
undefined behaviour.

Fixes: 3a0d465d4c53 ("eal: fix use-after-free on control thread creation")
---
 lib/librte_eal/common/eal_common_thread.c | 49 +++++++++++++----------
 1 file changed, 27 insertions(+), 22 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
index f9a8cf14d..a5089ae49 100644
--- a/lib/librte_eal/common/eal_common_thread.c
+++ b/lib/librte_eal/common/eal_common_thread.c
@@ -147,20 +147,25 @@ struct rte_thread_ctrl_params {
 	void *(*start_routine)(void *);
 	void *arg;
 	pthread_barrier_t configured;
+	unsigned int refcnt;
 };
 
+static void ctrl_params_free(struct rte_thread_ctrl_params *params)
+{
+	if (__atomic_sub_fetch(&params->refcnt, 1, __ATOMIC_ACQ_REL) == 0) {
+		(void)pthread_barrier_destroy(&params->configured);
+		free(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;
 
-	ret = pthread_barrier_wait(&params->configured);
-	if (ret == PTHREAD_BARRIER_SERIAL_THREAD) {
-		pthread_barrier_destroy(&params->configured);
-		free(params);
-	}
+	pthread_barrier_wait(&params->configured);
+	ctrl_params_free(params);
 
 	return start_routine(routine_arg);
 }
@@ -180,15 +185,18 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
 
 	params->start_routine = start_routine;
 	params->arg = arg;
+	params->refcnt = 2;
 
-	pthread_barrier_init(&params->configured, NULL, 2);
-
-	ret = pthread_create(thread, attr, rte_thread_init, (void *)params);
+	ret = pthread_barrier_init(&params->configured, NULL, 2);
 	if (ret != 0) {
 		free(params);
 		return -ret;
 	}
 
+	ret = pthread_create(thread, attr, rte_thread_init, (void *)params);
+	if (ret != 0)
+		goto fail;
+
 	if (name != NULL) {
 		ret = rte_thread_setname(*thread, name);
 		if (ret < 0)
@@ -197,24 +205,21 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
 	}
 
 	ret = pthread_setaffinity_np(*thread, sizeof(*cpuset), cpuset);
-	if (ret)
-		goto fail;
+	if (ret != 0)
+		goto fail_cancel;
 
-	ret = pthread_barrier_wait(&params->configured);
-	if (ret == PTHREAD_BARRIER_SERIAL_THREAD) {
-		pthread_barrier_destroy(&params->configured);
-		free(params);
-	}
+	pthread_barrier_wait(&params->configured);
+	ctrl_params_free(params);
 
 	return 0;
 
-fail:
-	if (PTHREAD_BARRIER_SERIAL_THREAD ==
-	    pthread_barrier_wait(&params->configured)) {
-		pthread_barrier_destroy(&params->configured);
-		free(params);
-	}
+fail_cancel:
 	pthread_cancel(*thread);
 	pthread_join(*thread, NULL);
+
+fail:
+	(void)pthread_barrier_destroy(&params->configured);
+	free(params);
+
 	return -ret;
 }
-- 
2.25.1


^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-06-03  5:00 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-05-21 15:49 [dpdk-stable] [PATCH 19.11.9 1/2] eal: fix race in control thread creation Luc Pelletier
2021-05-21 15:49 ` [dpdk-stable] [PATCH 19.11.9 2/2] eal: fix hang " Luc Pelletier
2021-06-03  5:00   ` Christian Ehrhardt
2021-06-03  4:59 ` [dpdk-stable] [PATCH 19.11.9 1/2] eal: fix race " Christian Ehrhardt

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