[PATCH 5.15 133/159] ksmbd: fix race condition from parallel smb2 logoff requests

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5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Namjae Jeon <linkinjeon@xxxxxxxxxx>

[ Upstream commit 7ca9da7d873ee8024e9548d3366101c2b6843eab ]

If parallel smb2 logoff requests come in before closing door, running
request count becomes more than 1 even though connection status is set to
KSMBD_SESS_NEED_RECONNECT. It can't get condition true, and sleep forever.
This patch fix race condition problem by returning error if connection
status was already set to KSMBD_SESS_NEED_RECONNECT.

Reported-by: luosili <rootlab@xxxxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/ksmbd/smb2pdu.c |   24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2164,17 +2164,17 @@ int smb2_session_logoff(struct ksmbd_wor
 
 	ksmbd_debug(SMB, "request\n");
 
-	sess_id = le64_to_cpu(req->hdr.SessionId);
-
-	rsp->StructureSize = cpu_to_le16(4);
-	err = ksmbd_iov_pin_rsp(work, rsp, sizeof(struct smb2_logoff_rsp));
-	if (err) {
-		rsp->hdr.Status = STATUS_INSUFFICIENT_RESOURCES;
+	ksmbd_conn_lock(conn);
+	if (!ksmbd_conn_good(conn)) {
+		ksmbd_conn_unlock(conn);
+		rsp->hdr.Status = STATUS_NETWORK_NAME_DELETED;
 		smb2_set_err_rsp(work);
-		return err;
+		return -ENOENT;
 	}
-
+	sess_id = le64_to_cpu(req->hdr.SessionId);
 	ksmbd_all_conn_set_status(sess_id, KSMBD_SESS_NEED_RECONNECT);
+	ksmbd_conn_unlock(conn);
+
 	ksmbd_close_session_fds(work);
 	ksmbd_conn_wait_idle(conn, sess_id);
 
@@ -2196,6 +2196,14 @@ int smb2_session_logoff(struct ksmbd_wor
 	ksmbd_free_user(sess->user);
 	sess->user = NULL;
 	ksmbd_all_conn_set_status(sess_id, KSMBD_SESS_NEED_NEGOTIATE);
+
+	rsp->StructureSize = cpu_to_le16(4);
+	err = ksmbd_iov_pin_rsp(work, rsp, sizeof(struct smb2_logoff_rsp));
+	if (err) {
+		rsp->hdr.Status = STATUS_INSUFFICIENT_RESOURCES;
+		smb2_set_err_rsp(work);
+		return err;
+	}
 	return 0;
 }
 






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