linux-kernel - [PATCH next] smb: client: Fix NULL vs ERR_PTR() returns in cifs_get_tcon

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Message-ID: <aKL5dUyf7UWcQNvW@stanley.mountain>
Date: Mon, 18 Aug 2025 12:59:17 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Wang Zhaolong <wangzhaolong@...weicloud.com>
Cc: Steve French <sfrench@...ba.org>, Paulo Alcantara <pc@...guebit.org>,
	Ronnie Sahlberg <ronniesahlberg@...il.com>,
	Shyam Prasad N <sprasad@...rosoft.com>, Tom Talpey <tom@...pey.com>,
	Bharath SM <bharathsm@...rosoft.com>, linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH next] smb: client: Fix NULL vs ERR_PTR() returns in
 cifs_get_tcon_super()

The cifs_get_tcon_super() function returns NULL on error but the caller
expect it to return error pointers instead.  Change it to return error
pointers.  Otherwise it results in a NULL pointer dereference.

Fixes: 0938b093b1ae ("smb: client: Fix mount deadlock by avoiding super block iteration in DFS reconnect")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 fs/smb/client/misc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c
index 3b6920a52daa..d73c36862e97 100644
--- a/fs/smb/client/misc.c
+++ b/fs/smb/client/misc.c
@@ -1116,7 +1116,7 @@ static struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon)
 	struct cifs_sb_info *cifs_sb;
 
 	if (!tcon)
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	spin_lock(&tcon->sb_list_lock);
 	list_for_each_entry(cifs_sb, &tcon->cifs_sb_list, tcon_sb_link) {
@@ -1141,7 +1141,7 @@ static struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon)
 	}
 	spin_unlock(&tcon->sb_list_lock);
 
-	return NULL;
+	return ERR_PTR(-ENOENT);
 }
 
 struct super_block *cifs_get_dfs_tcon_super(struct cifs_tcon *tcon)
-- 
2.47.2