linux-kernel - [PATCH AUTOSEL 6.2 18/18] cifs: missing lock when updating session status

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Date:   Tue,  9 May 2023 17:19:56 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Steve French <stfrench@...rosoft.com>,
        Paulo Alcantara <pc@...guebit.com>,
        Bharath SM <bharathsm@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>, sfrench@...ba.org,
        linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org
Subject: [PATCH AUTOSEL 6.2 18/18] cifs: missing lock when updating session status

From: Steve French <stfrench@...rosoft.com>

[ Upstream commit 943fb67b090212f1d3789eb7796b1c9045c62fd6 ]

Coverity noted a place where we were not grabbing
the ses_lock when setting (and checking) ses_status.

Addresses-Coverity: 1536833 ("Data race condition (MISSING_LOCK)")
Reviewed-by: Paulo Alcantara (SUSE) <pc@...guebit.com>
Reviewed-by: Bharath SM <bharathsm@...rosoft.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/cifs/connect.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 985e962cf0858..860e533ad1bf0 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1965,18 +1965,22 @@ void cifs_put_smb_ses(struct cifs_ses *ses)
 	/* ses_count can never go negative */
 	WARN_ON(ses->ses_count < 0);
 
+	spin_lock(&ses->ses_lock);
 	if (ses->ses_status == SES_GOOD)
 		ses->ses_status = SES_EXITING;
 
-	cifs_free_ipc(ses);
-
 	if (ses->ses_status == SES_EXITING && server->ops->logoff) {
+		spin_unlock(&ses->ses_lock);
+		cifs_free_ipc(ses);
 		xid = get_xid();
 		rc = server->ops->logoff(xid, ses);
 		if (rc)
 			cifs_server_dbg(VFS, "%s: Session Logoff failure rc=%d\n",
 				__func__, rc);
 		_free_xid(xid);
+	} else {
+		spin_unlock(&ses->ses_lock);
+		cifs_free_ipc(ses);
 	}
 
 	spin_lock(&cifs_tcp_ses_lock);
-- 
2.39.2