From: Namjae Jeon <linkinjeon@kernel.org>
Date: Wed, 3 May 2023 08:51:12 +0900
Subject: [PATCH] ksmbd: fix racy issue under cocurrent smb2 tree disconnect
References: bsc#1012628
Patch-mainline: 6.3.2
Git-commit: 30210947a343b6b3ca13adc9bfc88e1543e16dd5

commit 30210947a343b6b3ca13adc9bfc88e1543e16dd5 upstream.

There is UAF issue under cocurrent smb2 tree disconnect.
This patch introduce TREE_CONN_EXPIRE flags for tcon to avoid cocurrent
access.

Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-20592
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 fs/ksmbd/mgmt/tree_connect.c | 10 +++++++++-
 fs/ksmbd/mgmt/tree_connect.h |  3 +++
 fs/ksmbd/smb2pdu.c           |  3 ++-
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/fs/ksmbd/mgmt/tree_connect.c b/fs/ksmbd/mgmt/tree_connect.c
index 8ce17b3f..f19de20c 100644
--- a/fs/ksmbd/mgmt/tree_connect.c
+++ b/fs/ksmbd/mgmt/tree_connect.c
@@ -109,7 +109,15 @@ int ksmbd_tree_conn_disconnect(struct ksmbd_session *sess,
 struct ksmbd_tree_connect *ksmbd_tree_conn_lookup(struct ksmbd_session *sess,
 						  unsigned int id)
 {
-	return xa_load(&sess->tree_conns, id);
+	struct ksmbd_tree_connect *tcon;
+
+	tcon = xa_load(&sess->tree_conns, id);
+	if (tcon) {
+		if (test_bit(TREE_CONN_EXPIRE, &tcon->status))
+			tcon = NULL;
+	}
+
+	return tcon;
 }
 
 struct ksmbd_share_config *ksmbd_tree_conn_share(struct ksmbd_session *sess,
diff --git a/fs/ksmbd/mgmt/tree_connect.h b/fs/ksmbd/mgmt/tree_connect.h
index 0f97ddc1..700df36c 100644
--- a/fs/ksmbd/mgmt/tree_connect.h
+++ b/fs/ksmbd/mgmt/tree_connect.h
@@ -14,6 +14,8 @@ struct ksmbd_share_config;
 struct ksmbd_user;
 struct ksmbd_conn;
 
+#define TREE_CONN_EXPIRE		1
+
 struct ksmbd_tree_connect {
 	int				id;
 
@@ -25,6 +27,7 @@ struct ksmbd_tree_connect {
 
 	int				maximal_access;
 	bool				posix_extensions;
+	unsigned long			status;
 };
 
 struct ksmbd_tree_conn_status {
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 67b7e766..3bb7c705 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2048,11 +2048,12 @@ int smb2_tree_disconnect(struct ksmbd_work *work)
 
 	ksmbd_debug(SMB, "request\n");
 
-	if (!tcon) {
+	if (!tcon || test_and_set_bit(TREE_CONN_EXPIRE, &tcon->status)) {
 		struct smb2_tree_disconnect_req *req =
 			smb2_get_msg(work->request_buf);
 
 		ksmbd_debug(SMB, "Invalid tid %d\n", req->hdr.Id.SyncId.TreeId);
+
 		rsp->hdr.Status = STATUS_NETWORK_NAME_DELETED;
 		smb2_set_err_rsp(work);
 		return 0;
-- 
2.35.3