[PATCH 4.9 086/101] NFSv4: Revert commit 5f83d86cf531d ("NFSv4.x: Fix wraparound issues..")

From: Greg Kroah-Hartman
Date: Sun Jul 01 2018 - 14:09:43 EST


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

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

From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>

commit fc40724fc6731d90cc7fb6d62d66135f85a33dd2 upstream.

The correct behaviour for NFSv4 sequence IDs is to wrap around
to the value 0 after 0xffffffff.
See https://tools.ietf.org/html/rfc5661#section-2.10.6.1

Fixes: 5f83d86cf531d ("NFSv4.x: Fix wraparound issues when validing...")
Cc: stable@xxxxxxxxxxxxxxx # 4.6+
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/nfs/callback_proc.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -402,11 +402,8 @@ validate_seqid(const struct nfs4_slot_ta
return htonl(NFS4ERR_SEQ_FALSE_RETRY);
}

- /* Wraparound */
- if (unlikely(slot->seq_nr == 0xFFFFFFFFU)) {
- if (args->csa_sequenceid == 1)
- return htonl(NFS4_OK);
- } else if (likely(args->csa_sequenceid == slot->seq_nr + 1))
+ /* Note: wraparound relies on seq_nr being of type u32 */
+ if (likely(args->csa_sequenceid == slot->seq_nr + 1))
return htonl(NFS4_OK);

/* Misordered request */