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")
Signed-off-by: Gaoxiang Liu <liugaoxi...@huawei.com>
---
v2:
* Fix coding style issues.
v3:
* Add detailed log.
v4:
* Add the reason, when vhostuser port is created as server.
v5:
* Add detailed log when vhostuser port is created as client
v6:
* Add 'path' check before deleting listen fd
* Fix spelling issues
---
lib/vhost/socket.c | 108 ++++++++++++++++++++++-----------------------
1 file changed, 54 insertions(+), 54 deletions(-)
diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
index 5d0d728d5..27d5e8695 100644
--- a/lib/vhost/socket.c
+++ b/lib/vhost/socket.c
@@ -1023,66 +1023,66 @@ 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 (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;
+ }
+
+ 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);
- return 0;
+ 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);
--
2.32.0
