[SRU][J][PATCH 2/2] smb: client: fix potential UAF in smb2_is_valid_lease_break()

[Yuxuan Luo]

From: Paulo Alcantara <pc at manguebit.com>

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

Cc: stable at vger.kernel.org
Signed-off-by: Paulo Alcantara (Red Hat) <pc at manguebit.com>
Signed-off-by: Steve French <stfrench at microsoft.com>
(backported from commit 705c76fbf726c7a2f6ff9143d4013b18daaaebf1)
[yuxuan.luo: ignored context conflicts and added the if statement.]
CVE-2024-35864
Signed-off-by: Yuxuan Luo <yuxuan.luo at canonical.com>
---
 fs/cifs/smb2misc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index 8f409404aee1..c28241dcc950 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -604,6 +604,8 @@ smb2_is_valid_lease_break(char *buffer)
 	/* look up tcon based on tid & uid */
 	spin_lock(&cifs_tcp_ses_lock);
 	list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
+		if (cifs_ses_exiting(ses))
+			continue;
 		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
 			list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 				spin_lock(&tcon->open_file_lock);
-- 
2.43.0