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[74.15.213.92]) by smtp.gmail.com with ESMTPSA id 66sm19167731qkk.18.2021.04.07.08.53.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Apr 2021 08:53:24 -0700 (PDT) From: Luc Pelletier To: olivier.matz@6wind.com, jianfeng.tan@intel.com, Honnappa.Nagarahalli@arm.com Cc: dev@dpdk.org, Luc Pelletier , stable@dpdk.org Date: Wed, 7 Apr 2021 11:29:04 -0400 Message-Id: <20210407152903.130730-1-lucp.at.work@gmail.com> In-Reply-To: <20210407145722.GN1650@platinum> References: <20210407145722.GN1650@platinum> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [dpdk-dev] [PATCH v7] eal: fix race in ctrl thread creation X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 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") Cc: jianfeng.tan@intel.com Cc: stable@dpdk.org Signed-off-by: Luc Pelletier --- Hi Olivier, Olivier, thanks for pointing out that pthread_barrier_wait acts as a full memory barrier; I didn't know that was explicitly specified in the documentation. I've changed it to use a regular read/write. Hi Honnappa, I have not changed the code to use pthread_attr_setaffinity_np because the attr parameter is const. I could make a copy of the provided attributes and use that instead, but I think this would still violate the spirit of the API and, AFAICT, there's no official mechanism for copying a pthread_attr_t. Please let me know what you think. lib/librte_eal/common/eal_common_thread.c | 63 +++++++++++++---------- 1 file changed, 35 insertions(+), 28 deletions(-) diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c index 73a055902..d4e09f84b 100644 --- a/lib/librte_eal/common/eal_common_thread.c +++ b/lib/librte_eal/common/eal_common_thread.c @@ -170,25 +170,34 @@ 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(¶ms->refcnt, 1, __ATOMIC_ACQ_REL) == 0) { + pthread_barrier_destroy(¶ms->configured); + free(params); + } +} + 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; struct rte_thread_ctrl_params *params = arg; - void *(*start_routine)(void *) = params->start_routine; + void *(*start_routine)(void *); void *routine_arg = params->arg; __rte_thread_init(rte_lcore_id(), cpuset); - ret = pthread_barrier_wait(¶ms->configured); - if (ret == PTHREAD_BARRIER_SERIAL_THREAD) { - pthread_barrier_destroy(¶ms->configured); - free(params); - } + pthread_barrier_wait(¶ms->configured); + start_routine = params->start_routine; + ctrl_params_free(params); + + if (start_routine == NULL) + return NULL; return start_routine(routine_arg); } @@ -210,14 +219,15 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name, params->start_routine = start_routine; params->arg = arg; + params->refcnt = 2; - pthread_barrier_init(¶ms->configured, NULL, 2); + ret = pthread_barrier_init(¶ms->configured, NULL, 2); + if (ret != 0) + goto fail_no_barrier; ret = pthread_create(thread, attr, ctrl_thread_init, (void *)params); - if (ret != 0) { - free(params); - return -ret; - } + if (ret != 0) + goto fail_with_barrier; if (name != NULL) { ret = rte_thread_setname(*thread, name); @@ -227,25 +237,22 @@ 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) + params->start_routine = NULL; + pthread_barrier_wait(¶ms->configured); + ctrl_params_free(params); - ret = pthread_barrier_wait(¶ms->configured); - if (ret == PTHREAD_BARRIER_SERIAL_THREAD) { - pthread_barrier_destroy(¶ms->configured); - free(params); - } + if (ret != 0) + pthread_join(*thread, NULL); - return 0; + return -ret; + +fail_with_barrier: + pthread_barrier_destroy(¶ms->configured); + +fail_no_barrier: + free(params); -fail: - if (PTHREAD_BARRIER_SERIAL_THREAD == - pthread_barrier_wait(¶ms->configured)) { - pthread_barrier_destroy(¶ms->configured); - free(params); - } - pthread_cancel(*thread); - pthread_join(*thread, NULL); return -ret; } -- 2.25.1