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

[jianqi.ren.cn]

From: Paulo Alcantara <pc@xxxxxxxxxxxxx>

commit 58acd1f497162e7d282077f816faa519487be045 upstream.

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>
[This patch removes lock/unlock operation in routine cifs_dump_full_key()
for ses_lock is not present in v5.15 and not ported yet. ses->status
is protected by a global lock, cifs_tcp_ses_lock, in v5.15.]
Signed-off-by: Jianqi Ren <jianqi.ren.cn@xxxxxxxxxxxxx>
Signed-off-by: He Zhe <zhe.he@xxxxxxxxxxxxx>
---
Verified the build test
---
 fs/cifs/ioctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c
index 71883ba9e567..e846c18b71d2 100644
--- a/fs/cifs/ioctl.c
+++ b/fs/cifs/ioctl.c
@@ -232,7 +232,8 @@ static int cifs_dump_full_key(struct cifs_tcon *tcon, struct smb3_full_key_debug
 		spin_lock(&cifs_tcp_ses_lock);
 		list_for_each_entry(server_it, &cifs_tcp_ses_list, tcp_ses_list) {
 			list_for_each_entry(ses_it, &server_it->smb_ses_list, smb_ses_list) {
-				if (ses_it->Suid == out.session_id) {
+				if (ses_it->status != CifsExiting &&
+				    ses_it->Suid == out.session_id) {
 					ses = ses_it;
 					/*
 					 * since we are using the session outside the crit
-- 
2.25.1