[dpdk-dev] [PATCH] vhost: fix coredump on port deletion

[Gaoxiang Liu <gaoxiangliu0@163.com>]

The rte_vhost_driver_unregister() and vhost_user_read_cb()
can be called at the same time by 2 threads.
Eg thread1 calls rte_vhost_driver_unregister() and frees memory of conn,
then thread2 calls vhost_user_read_cb() and access invalid memory of
conn.

The fix is to move the "fdset_try_del" in front of free memory of conn ,
then avoid the race condition.

Fixes: 52d874dc6705 ("vhost: fix crash on closing in client mode")

Signed-off-by: Gaoxiang Liu <liugaoxiang@huawei.com>
---
 lib/vhost/socket.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
index 5d0d728d5..bc7278e8a 100644
--- a/lib/vhost/socket.c
+++ b/lib/vhost/socket.c
@@ -1024,6 +1024,19 @@ rte_vhost_driver_unregister(const char *path)
 	for (i = 0; i < vhost_user.vsocket_cnt; i++) {
 		struct vhost_user_socket *vsocket = vhost_user.vsockets[i];
 
+		if (vsocket->is_server) {
+			/*
+			 * If r/wcb is executing, release vhost_user's
+			 * mutex lock, and try again since the r/wcb
+			 * may use the mutex lock.
+			 */
+			if (fdset_try_del(&vhost_user.fdset, vsocket->socket_fd) == -1) {
+				pthread_mutex_unlock(&vhost_user.mutex);
+				goto again;
+			}
+		 } else if (vsocket->reconnect)
+			vhost_user_remove_reconnect(vsocket);
+
 		if (!strcmp(vsocket->path, path)) {
 			pthread_mutex_lock(&vsocket->conn_mutex);
 			for (conn = TAILQ_FIRST(&vsocket->conn_list);
@@ -1056,21 +1069,8 @@ rte_vhost_driver_unregister(const char *path)
 			pthread_mutex_unlock(&vsocket->conn_mutex);
 
 			if (vsocket->is_server) {
-				/*
-				 * If r/wcb is executing, release vhost_user's
-				 * mutex lock, and try again since the r/wcb
-				 * may use the mutex lock.
-				 */
-				if (fdset_try_del(&vhost_user.fdset,
-						vsocket->socket_fd) == -1) {
-					pthread_mutex_unlock(&vhost_user.mutex);
-					goto again;
-				}
-
 				close(vsocket->socket_fd);
 				unlink(path);
-			} else if (vsocket->reconnect) {
-				vhost_user_remove_reconnect(vsocket);
 			}
 
 			pthread_mutex_destroy(&vsocket->conn_mutex);
-- 
2.32.0