From: Namjae Jeon <linkinjeon@kernel.org>
Date: Tue, 2 May 2023 23:51:12 +0000 (+0900)
Subject: ksmbd: fix racy issue under cocurrent smb2 tree disconnect
X-Git-Tag: v6.2.15~573
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dc1c17716c099c90948ebb83e2170dd75a3be6b6;p=thirdparty%2Fkernel%2Fstable.git

ksmbd: fix racy issue under cocurrent smb2 tree disconnect

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>
---

diff --git a/fs/ksmbd/mgmt/tree_connect.c b/fs/ksmbd/mgmt/tree_connect.c
index 8ce17b3fb8dad..f19de20c2960c 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 0f97ddc1e39c0..700df36cf3e30 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 32a837014cbfc..61e47f66f2f2b 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2055,11 +2055,12 @@ 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;