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 accessd in vhost_user_read_cb().
It's a bug of both mode for vhost as server or client.
Eg 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
access invalid memory of socket while thread1 frees the memory of
vsocket.
Eg 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
access 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.
---
lib/vhost/socket.c | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
index 5d0d728d5..2eb8fcadd 100644
--- a/lib/vhost/socket.c
+++ b/lib/vhost/socket.c
@@ -1024,6 +1024,20 @@ 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 +1070,8 @@ 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
