From 451dc0fad83d07d194e688f52093c7e888d2e317 Mon Sep 17 00:00:00 2001 From: Gaoxiang Liu Date: Thu, 2 Sep 2021 23:45:53 +0800 Subject: [PATCH] vhost: fix crash on port deletion The rte_vhost_driver_unregister() and vhost_user_read_cb() can be called at the same time by 2 threads. when memory of vsocket is freed in rte_vhost_driver_unregister(), the invalid memory of vsocket is accessed in vhost_user_read_cb(). It's a bug of both mode for vhost as server or client. E.g., vhostuser port is created as server. Thread1 calls rte_vhost_driver_unregister(). Before the listen fd is deleted from poll waiting fds, "vhost-events" thread then calls vhost_user_server_new_connection(), then a new conn fd is added in fdset when trying to reconnect. "vhost-events" thread then calls vhost_user_read_cb() and accesses invalid memory of socket while thread1 frees the memory of vsocket. E.g., vhostuser port is created as client. Thread1 calls rte_vhost_driver_unregister(). Before vsocket of reconn is deleted from reconn list, "vhost_reconn" thread then calls vhost_user_add_connection() then a new conn fd is added in fdset when trying to reconnect. "vhost-events" thread then calls vhost_user_read_cb() and accesses invalid memory of socket while thread1 frees the memory of vsocket. The fix is to move the "fdset_try_del" in front of free memory of conn, then avoid the race condition. The core trace is: Program terminated with signal 11, Segmentation fault. Fixes: 52d874dc6705 ("vhost: fix crash on closing in client mode") Cc: stable@dpdk.org Signed-off-by: Gaoxiang Liu Reviewed-by: Chenbo Xia --- lib/vhost/socket.c | 107 ++++++++++++++++++++++----------------------- 1 file changed, 53 insertions(+), 54 deletions(-) diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c index 5d0d728d52..d6f9414c4d 100644 --- a/lib/vhost/socket.c +++ b/lib/vhost/socket.c @@ -1023,66 +1023,65 @@ again: for (i = 0; i < vhost_user.vsocket_cnt; i++) { struct vhost_user_socket *vsocket = vhost_user.vsockets[i]; + if (strcmp(vsocket->path, path)) + continue; - if (!strcmp(vsocket->path, path)) { - pthread_mutex_lock(&vsocket->conn_mutex); - for (conn = TAILQ_FIRST(&vsocket->conn_list); - conn != NULL; - conn = next) { - next = TAILQ_NEXT(conn, next); - - /* - * If r/wcb is executing, release vsocket's - * conn_mutex and vhost_user's mutex locks, and - * try again since the r/wcb may use the - * conn_mutex and mutex locks. - */ - if (fdset_try_del(&vhost_user.fdset, - conn->connfd) == -1) { - pthread_mutex_unlock( - &vsocket->conn_mutex); - pthread_mutex_unlock(&vhost_user.mutex); - goto again; - } - - VHOST_LOG_CONFIG(INFO, - "free connfd = %d for device '%s'\n", - conn->connfd, path); - close(conn->connfd); - vhost_destroy_device(conn->vid); - TAILQ_REMOVE(&vsocket->conn_list, conn, next); - free(conn); - } - 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); + 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); + } - pthread_mutex_destroy(&vsocket->conn_mutex); - vhost_user_socket_mem_free(vsocket); + pthread_mutex_lock(&vsocket->conn_mutex); + for (conn = TAILQ_FIRST(&vsocket->conn_list); + conn != NULL; + conn = next) { + next = TAILQ_NEXT(conn, next); - count = --vhost_user.vsocket_cnt; - vhost_user.vsockets[i] = vhost_user.vsockets[count]; - vhost_user.vsockets[count] = NULL; - pthread_mutex_unlock(&vhost_user.mutex); + /* + * If r/wcb is executing, release vsocket's + * conn_mutex and vhost_user's mutex locks, and + * try again since the r/wcb may use the + * conn_mutex and mutex locks. + */ + if (fdset_try_del(&vhost_user.fdset, + conn->connfd) == -1) { + pthread_mutex_unlock(&vsocket->conn_mutex); + pthread_mutex_unlock(&vhost_user.mutex); + goto again; + } - return 0; + VHOST_LOG_CONFIG(INFO, + "free connfd = %d for device '%s'\n", + conn->connfd, path); + close(conn->connfd); + vhost_destroy_device(conn->vid); + TAILQ_REMOVE(&vsocket->conn_list, conn, next); + free(conn); + } + pthread_mutex_unlock(&vsocket->conn_mutex); + + if (vsocket->is_server) { + close(vsocket->socket_fd); + unlink(path); } + + pthread_mutex_destroy(&vsocket->conn_mutex); + vhost_user_socket_mem_free(vsocket); + + count = --vhost_user.vsocket_cnt; + vhost_user.vsockets[i] = vhost_user.vsockets[count]; + vhost_user.vsockets[count] = NULL; + pthread_mutex_unlock(&vhost_user.mutex); + return 0; } pthread_mutex_unlock(&vhost_user.mutex); -- 2.20.1