[PATCH 5.15.y] smb: client: fix potential UAF in smb2_is_valid_oplock_break()

[Robert Garcia]

From: Paulo Alcantara <pc@xxxxxxxxxxxxx>

[ Upstream commit 22863485a4626ec6ecf297f4cc0aef709bc862e4 ]

Skip sessions that are being teared down (status == SES_EXITING) to
avoid UAF.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paulo Alcantara (Red Hat) <pc@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
[ Appropriate path used. ]
Signed-off-by: Robert Garcia <rob_garcia@xxxxxxx>
---
 fs/cifs/smb2misc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index b84e682b4cae..da32b3f6686b 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -679,6 +679,8 @@ smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
 	/* look up tcon based on tid & uid */
 	spin_lock(&cifs_tcp_ses_lock);
 	list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
+		if (cifs_ses_exiting(ses))
+			continue;
 		list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 
 			spin_lock(&tcon->open_file_lock);
-- 
2.34.1