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From: Olivier Matz <olivier.matz@6wind.com>
To: lucp.at.work@gmail.com
Cc: dev@dpdk.org, jianfeng.tan@intel.com, david.marchand@redhat.com,
	stable@dpdk.org
Subject: [dpdk-dev] [PATCH v2] eal: fix race in ctrl thread creation
Date: Thu, 25 Mar 2021 12:27:31 +0100
Message-ID: <20210325112731.16324-1-olivier.matz@6wind.com> (raw)
In-Reply-To: <20210324130422.92357-1-lucp.at.work@gmail.com>

As reported by Luc, there is a race where the barrier is destroyed by
one thread, while the other thread did not yet leave
pthread_barrier_wait.

This patch fixes the race condition by adding an atomic counter to
ensure that the barrier is destroyed only it is not used by any thread.

Fixes: 3a0d465d4c53 ("eal: fix use-after-free on control thread creation")
Cc: jianfeng.tan@intel.com
Cc: stable@dpdk.org

Reported-by: Luc Pelletier <lucp.at.work@gmail.com>
Signed-off-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---

Hi Luc,

Thank you for reporting this problem and submitting the patch.
I think the issue can be fixed without any loop, like in this
patch. What do you think?

Regards,
Olivier


 lib/librte_eal/common/eal_common_thread.c | 38 +++++++++++++----------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
index 73a055902a..891f825e87 100644
--- a/lib/librte_eal/common/eal_common_thread.c
+++ b/lib/librte_eal/common/eal_common_thread.c
@@ -170,11 +170,11 @@ struct rte_thread_ctrl_params {
 	void *(*start_routine)(void *);
 	void *arg;
 	pthread_barrier_t configured;
+	unsigned int barrier_refcnt;
 };
 
 static void *ctrl_thread_init(void *arg)
 {
-	int ret;
 	struct internal_config *internal_conf =
 		eal_get_internal_configuration();
 	rte_cpuset_t *cpuset = &internal_conf->ctrl_cpuset;
@@ -184,8 +184,9 @@ static void *ctrl_thread_init(void *arg)
 
 	__rte_thread_init(rte_lcore_id(), cpuset);
 
-	ret = pthread_barrier_wait(&params->configured);
-	if (ret == PTHREAD_BARRIER_SERIAL_THREAD) {
+	pthread_barrier_wait(&params->configured);
+	if (__atomic_sub_fetch(&params->barrier_refcnt, 1,
+				__ATOMIC_ACQ_REL) == 0) {
 		pthread_barrier_destroy(&params->configured);
 		free(params);
 	}
@@ -210,15 +211,17 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
 
 	params->start_routine = start_routine;
 	params->arg = arg;
-
-	pthread_barrier_init(&params->configured, NULL, 2);
-
-	ret = pthread_create(thread, attr, ctrl_thread_init, (void *)params);
+	__atomic_store_n(&params->barrier_refcnt, 2, __ATOMIC_RELEASE);
+	ret = pthread_barrier_init(&params->configured, NULL, 2);
 	if (ret != 0) {
 		free(params);
 		return -ret;
 	}
 
+	ret = pthread_create(thread, attr, ctrl_thread_init, (void *)params);
+	if (ret != 0)
+		goto fail;
+
 	if (name != NULL) {
 		ret = rte_thread_setname(*thread, name);
 		if (ret < 0)
@@ -227,25 +230,26 @@ 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_wait(&params->configured);
+	if (__atomic_sub_fetch(&params->barrier_refcnt, 1,
+				__ATOMIC_ACQ_REL) == 0) {
 		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);
-	}
+fail_cancel:
 	pthread_cancel(*thread);
 	pthread_join(*thread, NULL);
+
+fail:
+	pthread_barrier_destroy(&params->configured);
+	free(params);
+
 	return -ret;
 }
 
-- 
2.29.2


  reply	other threads:[~2021-03-25 11:28 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-24 13:04 [dpdk-dev] [PATCH] eal: fix possible UB on creation of ctrl thread Luc Pelletier
2021-03-25 11:27 ` Olivier Matz [this message]
2021-03-25 14:42   ` [dpdk-dev] [PATCH v2] eal: fix race in ctrl thread creation Luc Pelletier
2021-04-02  4:34   ` Honnappa Nagarahalli
2021-04-06 15:57 ` [dpdk-dev] [PATCH v3] eal: fix possible UB on creation of ctrl thread Luc Pelletier
2021-04-06 16:15 ` [dpdk-dev] [PATCH v3] eal: fix race in ctrl thread creation Luc Pelletier
2021-04-06 21:10   ` Honnappa Nagarahalli
2021-04-07 12:35     ` [dpdk-dev] [PATCH v4] " Luc Pelletier
2021-04-07 12:53       ` [dpdk-dev] [PATCH v5] " Luc Pelletier
2021-04-07 13:22         ` Luc Pelletier
2021-04-07 13:31         ` Olivier Matz
2021-04-07 14:42           ` [dpdk-dev] [PATCH v6] " Luc Pelletier
2021-04-07 14:57             ` Olivier Matz
2021-04-07 15:29               ` [dpdk-dev] [PATCH v7] " Luc Pelletier
2021-04-07 17:15                 ` Honnappa Nagarahalli
2021-04-07 15:15           ` [dpdk-dev] [PATCH v5] " Honnappa Nagarahalli
2021-04-07 20:16             ` [dpdk-dev] [PATCH 1/2] " Luc Pelletier
2021-04-08 14:17               ` Olivier Matz
2021-04-08 17:06               ` Honnappa Nagarahalli
2021-04-07 20:16             ` [dpdk-dev] [PATCH 2/2] eal: fix hang in ctrl thread creation error logic Luc Pelletier
2021-04-08 14:20               ` Olivier Matz
2021-04-08 18:01                 ` Luc Pelletier
2021-04-09  8:13                   ` David Marchand
2021-04-08 17:07               ` Honnappa Nagarahalli
2021-04-09 14:34               ` [dpdk-dev] [dpdk-stable] " David Marchand

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