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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

* [dpdk-stable] [PATCH 19.11.9 2/2] eal: fix hang in control thread creation
  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 ` 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
  1 sibling, 1 reply; 4+ messages in thread
From: Luc Pelletier @ 2021-05-21 15:49 UTC (permalink / raw)
  To: christian.ehrhardt, stable; +Cc: Luc Pelletier

[ upstream commit af68c1d699be6c369e296b775bdbf13ae18b79cc ]

The affinity of a control thread is set after it has been launched. If
setting the affinity fails, pthread_cancel is called followed by a call
to pthread_join, which can hang forever if the thread's start routine
doesn't call a pthread cancellation point.

This patch modifies the logic so that the control thread exits
gracefully if the affinity cannot be set successfully and removes the
call to pthread_cancel.

Fixes: 6383d2642b62 ("eal: set name when creating a control thread")
---
 lib/librte_eal/common/eal_common_thread.c | 29 +++++++++++++----------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
index a5089ae49..b1e5c2a08 100644
--- a/lib/librte_eal/common/eal_common_thread.c
+++ b/lib/librte_eal/common/eal_common_thread.c
@@ -161,12 +161,16 @@ static void ctrl_params_free(struct rte_thread_ctrl_params *params)
 static void *rte_thread_init(void *arg)
 {
 	struct rte_thread_ctrl_params *params = arg;
-	void *(*start_routine)(void *) = params->start_routine;
+	void *(*start_routine)(void *);
 	void *routine_arg = params->arg;
 
 	pthread_barrier_wait(&params->configured);
+	start_routine = params->start_routine;
 	ctrl_params_free(params);
 
+	if (start_routine == NULL)
+		return NULL;
+
 	return start_routine(routine_arg);
 }
 
@@ -188,14 +192,12 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
 	params->refcnt = 2;
 
 	ret = pthread_barrier_init(&params->configured, NULL, 2);
-	if (ret != 0) {
-		free(params);
-		return -ret;
-	}
+	if (ret != 0)
+		goto fail_no_barrier;
 
 	ret = pthread_create(thread, attr, rte_thread_init, (void *)params);
 	if (ret != 0)
-		goto fail;
+		goto fail_with_barrier;
 
 	if (name != NULL) {
 		ret = rte_thread_setname(*thread, name);
@@ -206,19 +208,22 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
 
 	ret = pthread_setaffinity_np(*thread, sizeof(*cpuset), cpuset);
 	if (ret != 0)
-		goto fail_cancel;
+		params->start_routine = NULL;
 
 	pthread_barrier_wait(&params->configured);
 	ctrl_params_free(params);
 
-	return 0;
+	if (ret != 0)
+		/* start_routine has been set to NULL above; */
+		/* ctrl thread will exit immediately */
+		pthread_join(*thread, NULL);
 
-fail_cancel:
-	pthread_cancel(*thread);
-	pthread_join(*thread, NULL);
+	return -ret;
 
-fail:
+fail_with_barrier:
 	(void)pthread_barrier_destroy(&params->configured);
+
+fail_no_barrier:
 	free(params);
 
 	return -ret;
-- 
2.25.1


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

* Re: [dpdk-stable] [PATCH 19.11.9 1/2] eal: fix race in control thread creation
  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  4:59 ` Christian Ehrhardt
  1 sibling, 0 replies; 4+ messages in thread
From: Christian Ehrhardt @ 2021-06-03  4:59 UTC (permalink / raw)
  To: Luc Pelletier; +Cc: dpdk stable

On Fri, May 21, 2021 at 5:49 PM Luc Pelletier <lucp.at.work@gmail.com> wrote:
>
> [ 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")
> ---

Thank you, applied to 19.11.9 (to become -rc2) now

>  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
>


-- 
Christian Ehrhardt
Staff Engineer, Ubuntu Server
Canonical Ltd

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

* Re: [dpdk-stable] [PATCH 19.11.9 2/2] eal: fix hang in control thread creation
  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
  0 siblings, 0 replies; 4+ messages in thread
From: Christian Ehrhardt @ 2021-06-03  5:00 UTC (permalink / raw)
  To: Luc Pelletier; +Cc: dpdk stable

On Fri, May 21, 2021 at 5:49 PM Luc Pelletier <lucp.at.work@gmail.com> wrote:
>
> [ upstream commit af68c1d699be6c369e296b775bdbf13ae18b79cc ]
>
> The affinity of a control thread is set after it has been launched. If
> setting the affinity fails, pthread_cancel is called followed by a call
> to pthread_join, which can hang forever if the thread's start routine
> doesn't call a pthread cancellation point.
>
> This patch modifies the logic so that the control thread exits
> gracefully if the affinity cannot be set successfully and removes the
> call to pthread_cancel.
>
> Fixes: 6383d2642b62 ("eal: set name when creating a control thread")
> ---

Thank you, applied to 19.11.9 (to become -rc2) now

>  lib/librte_eal/common/eal_common_thread.c | 29 +++++++++++++----------
>  1 file changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
> index a5089ae49..b1e5c2a08 100644
> --- a/lib/librte_eal/common/eal_common_thread.c
> +++ b/lib/librte_eal/common/eal_common_thread.c
> @@ -161,12 +161,16 @@ static void ctrl_params_free(struct rte_thread_ctrl_params *params)
>  static void *rte_thread_init(void *arg)
>  {
>         struct rte_thread_ctrl_params *params = arg;
> -       void *(*start_routine)(void *) = params->start_routine;
> +       void *(*start_routine)(void *);
>         void *routine_arg = params->arg;
>
>         pthread_barrier_wait(&params->configured);
> +       start_routine = params->start_routine;
>         ctrl_params_free(params);
>
> +       if (start_routine == NULL)
> +               return NULL;
> +
>         return start_routine(routine_arg);
>  }
>
> @@ -188,14 +192,12 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
>         params->refcnt = 2;
>
>         ret = pthread_barrier_init(&params->configured, NULL, 2);
> -       if (ret != 0) {
> -               free(params);
> -               return -ret;
> -       }
> +       if (ret != 0)
> +               goto fail_no_barrier;
>
>         ret = pthread_create(thread, attr, rte_thread_init, (void *)params);
>         if (ret != 0)
> -               goto fail;
> +               goto fail_with_barrier;
>
>         if (name != NULL) {
>                 ret = rte_thread_setname(*thread, name);
> @@ -206,19 +208,22 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
>
>         ret = pthread_setaffinity_np(*thread, sizeof(*cpuset), cpuset);
>         if (ret != 0)
> -               goto fail_cancel;
> +               params->start_routine = NULL;
>
>         pthread_barrier_wait(&params->configured);
>         ctrl_params_free(params);
>
> -       return 0;
> +       if (ret != 0)
> +               /* start_routine has been set to NULL above; */
> +               /* ctrl thread will exit immediately */
> +               pthread_join(*thread, NULL);
>
> -fail_cancel:
> -       pthread_cancel(*thread);
> -       pthread_join(*thread, NULL);
> +       return -ret;
>
> -fail:
> +fail_with_barrier:
>         (void)pthread_barrier_destroy(&params->configured);
> +
> +fail_no_barrier:
>         free(params);
>
>         return -ret;
> --
> 2.25.1
>


-- 
Christian Ehrhardt
Staff Engineer, Ubuntu Server
Canonical Ltd

^ 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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