[dpdk-dev] [PATCH v2] eal: fix use-after-free issue on thread creation
Olivier Matz
olivier.matz at 6wind.com
Wed May 2 13:24:17 CEST 2018
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 <maxime.coquelin at redhat.com>
> Reported-by: Lei Yao <lei.a.yao at intel.com>
> Suggested-by: Stephen Hemminger <stephen at networkplumber.org>
> Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com>
> ---
> 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
>
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