[PATCH AUTOSEL 6.4 4/4] cifs: fix session state check in reconnect to avoid use-after-free issue

[Sasha Levin <sashal@kernel.org>]

From: Winston Wen <wentao@uniontech.com>

[ Upstream commit 99f280700b4cc02d5f141b8d15f8e9fad0418f65 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/smb/client/smb2pdu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 17fe212ab895d..e04766fe6f803 100644
--- 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;
 
-- 
2.39.2