[patch 02/71] NFSD: Dont hold unrefcounted creds over call to nfsd_setuser()

[Greg KH]

2.6.30-stable review patch.  If anyone has any objections, please let us know.

------------------

From: David Howells <dhowells@xxxxxxxxxx>

commit 033a666ccb842ab4134fcd0c861d5ba9f5d6bf3a upstream.

nfsd_open() gets an unrefcounted pointer to the current process's effective
credentials at the top of the function, then calls nfsd_setuser() via
fh_verify() - which may replace and destroy the current process's effective
credentials - and then passes the unrefcounted pointer to dentry_open() - but
the credentials may have been destroyed by this point.

Instead, the value from current_cred() should be passed directly to
dentry_open() as one of its arguments, rather than being cached in a variable.

Possibly fh_verify() should return the creds to use.

This is a regression introduced by
745ca2475a6ac596e3d8d37c2759c0fbe2586227 "CRED: Pass credentials through
dentry_open()".

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Tested-and-Verified-By: Steve Dickson <steved@xxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/nfsd/vfs.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -677,7 +677,6 @@ __be32
 nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
 			int access, struct file **filp)
 {
-	const struct cred *cred = current_cred();
 	struct dentry	*dentry;
 	struct inode	*inode;
 	int		flags = O_RDONLY|O_LARGEFILE;
@@ -732,7 +731,7 @@ nfsd_open(struct svc_rqst *rqstp, struct
 		vfs_dq_init(inode);
 	}
 	*filp = dentry_open(dget(dentry), mntget(fhp->fh_export->ex_path.mnt),
-			    flags, cred);
+			    flags, current_cred());
 	if (IS_ERR(*filp))
 		host_err = PTR_ERR(*filp);
 out_nfserr:


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