From 61c8c52ced763e16f2c1482ee5a7f4e162c5c4ca Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Tue, 21 Apr 2015 15:25:39 -0400
Subject: [PATCH] nfsd4: disallow SEEK with special stateids

[ Upstream commit 980608fb50aea34993ba956b71cd4602aa42b14b ]

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@Netapp.com>
Cc: stable@vger.kernel.org
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
 fs/nfsd/nfs4proc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 0beb023..6ed5859 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1028,6 +1028,8 @@ nfsd4_seek(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		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:
-- 
2.7.4