linux-kernel - [PATCH 02/06] 9p: fix fid refcount leak in v9fs_vfs_get

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Message-Id: <20220612085330.1451496-3-asmadeus@codewreck.org>
Date:   Sun, 12 Jun 2022 17:53:25 +0900
From:   Dominique Martinet <asmadeus@...ewreck.org>
To:     Christian Schoenebeck <linux_oss@...debyte.com>,
        Tyler Hicks <tyhicks@...ux.microsoft.com>,
        Eric Van Hensbergen <ericvh@...il.com>,
        Latchesar Ionkov <lucho@...kov.net>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        Jianyong Wu <jianyong.wu@....com>
Cc:     v9fs-developer@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: [PATCH 02/06] 9p: fix fid refcount leak in v9fs_vfs_get_link

we check for protocol version later than required, after a fid has
been obtained. Just move the version check earlier.

Fixes: 6636b6dcc3db ("9p: add refcount to p9_fid struct")
Cc: stable@...r.kernel.org
Signed-off-by: Dominique Martinet <asmadeus@...ewreck.org>
---
 fs/9p/vfs_inode.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 55367ecb9442..18c780ffd4b5 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -1250,15 +1250,15 @@ static const char *v9fs_vfs_get_link(struct dentry *dentry,
 		return ERR_PTR(-ECHILD);
 
 	v9ses = v9fs_dentry2v9ses(dentry);
-	fid = v9fs_fid_lookup(dentry);
+	if (!v9fs_proto_dotu(v9ses))
+		return ERR_PTR(-EBADF);
+
 	p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);
+	fid = v9fs_fid_lookup(dentry);
 
 	if (IS_ERR(fid))
 		return ERR_CAST(fid);
 
-	if (!v9fs_proto_dotu(v9ses))
-		return ERR_PTR(-EBADF);
-
 	st = p9_client_stat(fid);
 	p9_client_clunk(fid);
 	if (IS_ERR(st))
-- 
2.35.1