linux-kernel - [PATCH 5.7 146/166] cifs: fix reference leak for tlink

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Date:   Tue, 14 Jul 2020 20:45:11 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ronnie Sahlberg <lsahlber@...hat.com>,
        Steve French <stfrench@...rosoft.com>,
        Aurelien Aptel <aaptel@...e.com>
Subject: [PATCH 5.7 146/166] cifs: fix reference leak for tlink

From: Ronnie Sahlberg <lsahlber@...hat.com>

commit a77592a70081edb58a95b9da18fd5a2882a25666 upstream.

Don't leak a reference to tlink during the NOTIFY ioctl

Signed-off-by: Ronnie Sahlberg <lsahlber@...hat.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Reviewed-by: Aurelien Aptel <aaptel@...e.com>
CC: Stable <stable@...r.kernel.org> # v5.6+
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/cifs/ioctl.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/fs/cifs/ioctl.c
+++ b/fs/cifs/ioctl.c
@@ -169,6 +169,7 @@ long cifs_ioctl(struct file *filep, unsi
 	unsigned int xid;
 	struct cifsFileInfo *pSMBFile = filep->private_data;
 	struct cifs_tcon *tcon;
+	struct tcon_link *tlink;
 	struct cifs_sb_info *cifs_sb;
 	__u64	ExtAttrBits = 0;
 	__u64   caps;
@@ -307,13 +308,19 @@ long cifs_ioctl(struct file *filep, unsi
 				break;
 			}
 			cifs_sb = CIFS_SB(inode->i_sb);
-			tcon = tlink_tcon(cifs_sb_tlink(cifs_sb));
+			tlink = cifs_sb_tlink(cifs_sb);
+			if (IS_ERR(tlink)) {
+				rc = PTR_ERR(tlink);
+				break;
+			}
+			tcon = tlink_tcon(tlink);
 			if (tcon && tcon->ses->server->ops->notify) {
 				rc = tcon->ses->server->ops->notify(xid,
 						filep, (void __user *)arg);
 				cifs_dbg(FYI, "ioctl notify rc %d\n", rc);
 			} else
 				rc = -EOPNOTSUPP;
+			cifs_put_tlink(tlink);
 			break;
 		default:
 			cifs_dbg(FYI, "unsupported ioctl\n");