eal: fix thread race in control thread creation
Checks
Commit Message
When ctrl_thread_init transitions params->ctrl_thread_status from
CTRL_THREAD_LAUNCHING the creating thread and new thread may run
concurrently leading to unsynchronized access to params.
This permits races for both the failure and success paths after
ctrl_thread_status is stored.
* params->ret may be loaded in ctrl_thread_init failure path
* params->arg may be loaded in ctrl_thread_start or
control_thread_start when calling start_routine.
for ctrl_thread_init remove the params->ret load and just return 1 since
it is only interpreted as a indicator of success / failure of
ctrl_thread_init.
for {ctrl,control}_thread_start store param->arg in stack allocated
storage prior to calling ctrl_thread_init and use the copy when calling
start_routine.
for control_thread_start if ctrl_thread_init fails just return 0 instead
of loading params->ret, since the value returned is unused when
ctrl_thread_status is set to CTRL_THREAD_ERROR when ctrl_thread_init
fails.
Fixes: 878b7468eacb ("eal: add platform agnostic control thread API")
Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
---
lib/eal/common/eal_common_thread.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
Comments
On Mon, Feb 27, 2023 at 6:17 PM Tyler Retzlaff
<roretzla@linux.microsoft.com> wrote:
>
> When ctrl_thread_init transitions params->ctrl_thread_status from
> CTRL_THREAD_LAUNCHING the creating thread and new thread may run
> concurrently leading to unsynchronized access to params.
>
> This permits races for both the failure and success paths after
> ctrl_thread_status is stored.
> * params->ret may be loaded in ctrl_thread_init failure path
> * params->arg may be loaded in ctrl_thread_start or
> control_thread_start when calling start_routine.
>
> for ctrl_thread_init remove the params->ret load and just return 1 since
For*
> it is only interpreted as a indicator of success / failure of
> ctrl_thread_init.
>
> for {ctrl,control}_thread_start store param->arg in stack allocated
For*
> storage prior to calling ctrl_thread_init and use the copy when calling
> start_routine.
>
> for control_thread_start if ctrl_thread_init fails just return 0 instead
For*
> of loading params->ret, since the value returned is unused when
> ctrl_thread_status is set to CTRL_THREAD_ERROR when ctrl_thread_init
> fails.
>
> Fixes: 878b7468eacb ("eal: add platform agnostic control thread API")
>
> Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>
Thanks Tyler.
@@ -256,7 +256,7 @@ static int ctrl_thread_init(void *arg)
if (params->ret != 0) {
__atomic_store_n(¶ms->ctrl_thread_status,
CTRL_THREAD_ERROR, __ATOMIC_RELEASE);
- return params->ret;
+ return 1;
}
__atomic_store_n(¶ms->ctrl_thread_status,
@@ -268,23 +268,25 @@ static int ctrl_thread_init(void *arg)
static void *ctrl_thread_start(void *arg)
{
struct rte_thread_ctrl_params *params = arg;
+ void *start_arg = params->arg;
void *(*start_routine)(void *) = params->u.ctrl_start_routine;
if (ctrl_thread_init(arg) != 0)
return NULL;
- return start_routine(params->arg);
+ return start_routine(start_arg);
}
static uint32_t control_thread_start(void *arg)
{
struct rte_thread_ctrl_params *params = arg;
+ void *start_arg = params->arg;
rte_thread_func start_routine = params->u.control_start_routine;
if (ctrl_thread_init(arg) != 0)
- return params->ret;
+ return 0;
- return start_routine(params->arg);
+ return start_routine(start_arg);
}
int