From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olivier Matz Subject: Re: [PATCH v2] eal: fix use-after-free issue on thread creation Date: Wed, 2 May 2018 13:24:17 +0200 Message-ID: <20180502112417.shlwamchx4as4sqw@neon> References: <1525255198-20906-1-git-send-email-jianfeng.tan@intel.com> <1525256270-23138-1-git-send-email-jianfeng.tan@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: dev@dpdk.org, anatoly.burakov@intel.com, thomas@monjalon.net To: Jianfeng Tan Return-path: Received: from mail.droids-corp.org (zoll.droids-corp.org [94.23.50.67]) by dpdk.org (Postfix) with ESMTP id 153EC23C for ; Wed, 2 May 2018 13:24:20 +0200 (CEST) Content-Disposition: inline In-Reply-To: <1525256270-23138-1-git-send-email-jianfeng.tan@intel.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi Jianfeng, On Wed, May 02, 2018 at 10:17:50AM +0000, Jianfeng Tan wrote: > 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 > Reported-by: Lei Yao > Suggested-by: Stephen Hemminger > Signed-off-by: Jianfeng Tan > --- > v1->v2: > - Destroy barrier if failure happens. > lib/librte_eal/common/eal_common_thread.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c > index de69452..5f0c61f 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(¶ms->configured); > + ret = pthread_barrier_wait(¶ms->configured); > + if (ret == PTHREAD_BARRIER_SERIAL_THREAD) { > + pthread_barrier_destroy(¶ms->configured); > + free(params); > + } > > return start_routine(routine_arg); > } > @@ -204,12 +209,16 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name, > if (ret < 0) > goto fail; > > - pthread_barrier_wait(¶ms->configured); > - free(params); > + ret = pthread_barrier_wait(¶ms->configured); > + if (ret == PTHREAD_BARRIER_SERIAL_THREAD) { > + pthread_barrier_destroy(¶ms->configured); > + free(params); > + } > > return 0; > > fail: > + pthread_barrier_destroy(¶ms->configured); I think we should have the same code than above in the fail case: ret = pthread_barrier_wait(¶ms->configured); if (ret == PTHREAD_BARRIER_SERIAL_THREAD) { pthread_barrier_destroy(¶ms->configured); free(params); } Else, the child will wait forever on the barrier on failure. This can be tested with this standalone program: https://www.droids-corp.org/~zer0/hidden/ctrl_thread.c gcc -W -Wall -Werror -Wextra -pthread ctrl_thread.c ./a.out -> fail gcc -W -Wall -Werror -Wextra -pthread -DFIX ctrl_thread.c ./a.out -> ok > pthread_cancel(*thread); > pthread_join(*thread, NULL); > free(params); > -- > 2.7.4 >