cifs: fix session state check in reconnect to avoid use-after-free issue

Don't collect exiting session in smb2_reconnect_server(), because it
will be released soon.

Note that the exiting session will stay in server->smb_ses_list until
it complete the cifs_free_ipc() and logoff() and then delete itself
from the list.

Signed-off-by: Winston Wen <wentao@uniontech.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 17fe212ab895d73a12c07f5929f91030ac5cc7a6..e04766fe6f803d220168b5c8f0299cdcb0e13bcd 100644 (file)
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -3797,6 +3797,12 @@ void smb2_reconnect_server(struct work_struct *work)
 
        spin_lock(&cifs_tcp_ses_lock);
        list_for_each_entry(ses, &pserver->smb_ses_list, smb_ses_list) {
+               spin_lock(&ses->ses_lock);
+               if (ses->ses_status == SES_EXITING) {
+                       spin_unlock(&ses->ses_lock);
+                       continue;
+               }
+               spin_unlock(&ses->ses_lock);
 
                tcon_selected = false;