From: "J. Bruce Fields" <bfields@redhat.com>
Date: Mon, 26 Nov 2018 11:36:52 -0500
Subject: [PATCH] lockd: fix decoding of TEST results
Git-commit: b8db159239b3f51e2b909859935cc25cb3ff3eed
Patch-mainline: v5.0
References: git-fixes

We fail to advance the read pointer when reading the stat.oh field that
identifies the lock-holder in a TEST result.

This turns out not to matter if the server is knfsd, which always
returns a zero-length field.  But other servers (Ganesha is an example)
may not do this.  The result is bad values in fcntl F_GETLK results.

Fix this.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/lockd/clnt4xdr.c |   22 ++++++----------------
 fs/lockd/clntxdr.c  |   22 ++++++----------------
 2 files changed, 12 insertions(+), 32 deletions(-)

--- a/fs/lockd/clnt4xdr.c
+++ b/fs/lockd/clnt4xdr.c
@@ -127,24 +127,14 @@ static void encode_netobj(struct xdr_str
 static int decode_netobj(struct xdr_stream *xdr,
 			 struct xdr_netobj *obj)
 {
-	u32 length;
-	__be32 *p;
+	ssize_t ret;
 
-	p = xdr_inline_decode(xdr, 4);
-	if (unlikely(p == NULL))
-		goto out_overflow;
-	length = be32_to_cpup(p++);
-	if (unlikely(length > XDR_MAX_NETOBJ))
-		goto out_size;
-	obj->len = length;
-	obj->data = (u8 *)p;
+	ret = xdr_stream_decode_opaque_inline(xdr, (void *)&obj->data,
+						XDR_MAX_NETOBJ);
+	if (unlikely(ret < 0))
+		return -EIO;
+	obj->len = ret;
 	return 0;
-out_size:
-	dprintk("NFS: returned netobj was too long: %u\n", length);
-	return -EIO;
-out_overflow:
-	print_overflow_msg(__func__, xdr);
-	return -EIO;
 }
 
 /*
--- a/fs/lockd/clntxdr.c
+++ b/fs/lockd/clntxdr.c
@@ -124,24 +124,14 @@ static void encode_netobj(struct xdr_str
 static int decode_netobj(struct xdr_stream *xdr,
 			 struct xdr_netobj *obj)
 {
-	u32 length;
-	__be32 *p;
+	ssize_t ret;
 
-	p = xdr_inline_decode(xdr, 4);
-	if (unlikely(p == NULL))
-		goto out_overflow;
-	length = be32_to_cpup(p++);
-	if (unlikely(length > XDR_MAX_NETOBJ))
-		goto out_size;
-	obj->len = length;
-	obj->data = (u8 *)p;
+	ret = xdr_stream_decode_opaque_inline(xdr, (void *)&obj->data,
+			XDR_MAX_NETOBJ);
+	if (unlikely(ret < 0))
+		return -EIO;
+	obj->len = ret;
 	return 0;
-out_size:
-	dprintk("NFS: returned netobj was too long: %u\n", length);
-	return -EIO;
-out_overflow:
-	print_overflow_msg(__func__, xdr);
-	return -EIO;
 }
 
 /*