staging/lustre/ptlrpc: race in pinger (use-after-free situation)

The race is result of use-after-free situation:

~ ptlrpc_stop_pinger()          ~ ptlrpc_pinger_main()
---------------------------------------------------------------
thread_set_flags(SVC_STOPPING)
cfs_waitq_signal(pinger_thread) ...
...                             thread_set_flags(SVC_STOPPED)
l_wait_event(thread_is_stopped)
OBD_FREE_PTR(pinger_thread)
...                             cfs_waitq_signal(pinger_thread)
---------------------------------------------------------------

The memory used by pinger_thread might have been freed and
reallocated to something else, when ptlrpc_pinger_main()
used it in cvs_waitq_signal().

Signed-off-by: Li Wei <wei.g.li@intel.com>
Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3032
Lustre-change: http://review.whamcloud.com/6040
Reviewed-by: Faccini Bruno <bruno.faccini@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/ptlrpc/pinger.c b/drivers/staging/lustre/lustre/ptlrpc/pinger.c
index ef5269aee0deaff8c40c69adc2c4ee582f9e4370..f521251a1a6e906b9477999b986760a65d1c5950 100644 (file)
--- a/drivers/staging/lustre/lustre/ptlrpc/pinger.c
+++ b/drivers/staging/lustre/lustre/ptlrpc/pinger.c
@@ -369,7 +369,7 @@ static int ptlrpc_pinger_main(void *arg)
        return 0;
 }
 
-static struct ptlrpc_thread *pinger_thread = NULL;
+static struct ptlrpc_thread pinger_thread;
 
 int ptlrpc_start_pinger(void)
 {
@@ -377,29 +377,25 @@ int ptlrpc_start_pinger(void)
        int rc;
        ENTRY;
 
-       if (pinger_thread != NULL)
+       if (!thread_is_init(&pinger_thread) &&
+           !thread_is_stopped(&pinger_thread))
                RETURN(-EALREADY);
 
-       OBD_ALLOC_PTR(pinger_thread);
-       if (pinger_thread == NULL)
-               RETURN(-ENOMEM);
-       init_waitqueue_head(&pinger_thread->t_ctl_waitq);
+       init_waitqueue_head(&pinger_thread.t_ctl_waitq);
        init_waitqueue_head(&suspend_timeouts_waitq);
 
-       strcpy(pinger_thread->t_name, "ll_ping");
+       strcpy(pinger_thread.t_name, "ll_ping");
 
        /* CLONE_VM and CLONE_FILES just avoid a needless copy, because we
         * just drop the VM and FILES in cfs_daemonize_ctxt() right away. */
        rc = PTR_ERR(kthread_run(ptlrpc_pinger_main,
-                                pinger_thread, pinger_thread->t_name));
+                                &pinger_thread, pinger_thread.t_name));
        if (IS_ERR_VALUE(rc)) {
                CERROR("cannot start thread: %d\n", rc);
-               OBD_FREE(pinger_thread, sizeof(*pinger_thread));
-               pinger_thread = NULL;
                RETURN(rc);
        }
-       l_wait_event(pinger_thread->t_ctl_waitq,
-                    thread_is_running(pinger_thread), &lwi);
+       l_wait_event(pinger_thread.t_ctl_waitq,
+                    thread_is_running(&pinger_thread), &lwi);
 
        if (suppress_pings)
                CWARN("Pings will be suppressed at the request of the "
@@ -419,20 +415,17 @@ int ptlrpc_stop_pinger(void)
        int rc = 0;
        ENTRY;
 
-       if (pinger_thread == NULL)
+       if (!thread_is_init(&pinger_thread) &&
+           !thread_is_stopped(&pinger_thread))
                RETURN(-EALREADY);
 
        ptlrpc_pinger_remove_timeouts();
-       mutex_lock(&pinger_mutex);
-       thread_set_flags(pinger_thread, SVC_STOPPING);
-       wake_up(&pinger_thread->t_ctl_waitq);
-       mutex_unlock(&pinger_mutex);
+       thread_set_flags(&pinger_thread, SVC_STOPPING);
+       wake_up(&pinger_thread.t_ctl_waitq);
 
-       l_wait_event(pinger_thread->t_ctl_waitq,
-                    thread_is_stopped(pinger_thread), &lwi);
+       l_wait_event(pinger_thread.t_ctl_waitq,
+                    thread_is_stopped(&pinger_thread), &lwi);
 
-       OBD_FREE_PTR(pinger_thread);
-       pinger_thread = NULL;
        RETURN(rc);
 }
 
@@ -617,8 +610,8 @@ int ptlrpc_pinger_remove_timeouts(void)
 
 void ptlrpc_pinger_wake_up()
 {
-       thread_add_flags(pinger_thread, SVC_EVENT);
-       wake_up(&pinger_thread->t_ctl_waitq);
+       thread_add_flags(&pinger_thread, SVC_EVENT);
+       wake_up(&pinger_thread.t_ctl_waitq);
 }
 
 /* Ping evictor thread */