[PATCH 4.0 200/220] nfsd4: disallow SEEK with special stateids

[Greg Kroah-Hartman]

4.0-stable review patch.  If anyone has any objections, please let me know.

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

From: "J. Bruce Fields" <bfields@xxxxxxxxxx>

commit 980608fb50aea34993ba956b71cd4602aa42b14b upstream.

If the client uses a special stateid then we'll pass a NULL file to
vfs_llseek.

Fixes: 24bab491220f " NFSD: Implement SEEK"
Cc: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Reported-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/nfsd/nfs4proc.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1071,6 +1071,8 @@ nfsd4_seek(struct svc_rqst *rqstp, struc
 		dprintk("NFSD: nfsd4_seek: couldn't process stateid!\n");
 		return status;
 	}
+	if (!file)
+		return nfserr_bad_stateid;
 
 	switch (seek->seek_whence) {
 	case NFS4_CONTENT_DATA:


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