From: Al Viro <viro@zeniv.linux.org.uk>
Date: Wed, 20 Sep 2023 02:28:16 +0000 (-0400)
Subject: cifs_get_link(): bail out in unsafe case
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0511fdb4a378183ca18a9678d3d9044c8ec592c2;p=linux.git

cifs_get_link(): bail out in unsafe case

->d_revalidate() bails out there, anyway.  It's not enough
to prevent getting into ->get_link() in RCU mode, but that
could happen only in a very contrieved setup.  Not worth
trying to do anything fancy here unless ->d_revalidate()
stops kicking out of RCU mode at least in some cases.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c
index e902de4e475af..630e74628dfed 100644
--- a/fs/smb/client/cifsfs.c
+++ b/fs/smb/client/cifsfs.c
@@ -1172,6 +1172,9 @@ const char *cifs_get_link(struct dentry *dentry, struct inode *inode,
 {
 	char *target_path;
 
+	if (!dentry)
+		return ERR_PTR(-ECHILD);
+
 	target_path = kmalloc(PATH_MAX, GFP_KERNEL);
 	if (!target_path)
 		return ERR_PTR(-ENOMEM);