nfs: Fix argument typo to avoid a crash

A typo resulted in the wrong argument for a bytewise
comparison that could result in a crash if
the incorrect argument was not a valid pointer.

This patch fixes the argument.

While investigating this, I noticed that the
correct argument was not being filled in as
required, so this patch fixes that, as well.

Somehow, recovery from a NFSv4.1/4.2 server
crash worked during testing, so this was not
detected.  The bug/patch only affects NFS
client mounts using NFSv4.1/4.2.

PR:	294925
Reported by:	Jov <amutu@amutu.com>
MFC after:	3 days

sys/fs/nfs/nfs_commonkrpc.c

@@ -1265,8 +1265,9 @@ newnfs_request(struct nfsrv_descript *nd, struct nfsmount *nmp,
 					goto out;
 				}
 				sep = NFSMNT_MDSSESSION(nmp);
-				if (bcmp(sep->nfsess_sessionid, nd->nd_sequence,
-				    NFSX_V4SESSIONID) == 0) {
+				if (bcmp(sep->nfsess_sessionid,
+				    nd->nd_sessionid, NFSX_V4SESSIONID) == 0 &&
+				    sep->nfsess_defunct == 0) {
 					printf("Initiate recovery. If server "
 					    "has not rebooted, "
 					    "check NFS clients for unique "

sys/fs/nfs/nfs_commonsubs.c

@@ -368,6 +368,7 @@ nfscl_reqstart(struct nfsrv_descript *nd, int procnum, struct nfsmount *nmp,
 	 * First, fill in some of the fields of nd.
 	 */
 	nd->nd_slotseq = NULL;
+	NFSBZERO(nd->nd_sessionid, NFSX_V4SESSIONID);
 	if (vers == NFS_VER4) {
 		nd->nd_flag = ND_NFSV4 | ND_NFSCL;
 		if (minorvers == NFSV41_MINORVERSION)
@@ -5348,6 +5349,7 @@ nfsv4_setsequence(struct nfsmount *nmp, struct nfsrv_descript *nd,
 	NFSM_BUILD(tl, uint32_t *, NFSX_V4SESSIONID + 4 * NFSX_UNSIGNED);
 	nd->nd_sequence = tl;
 	bcopy(sessionid, tl, NFSX_V4SESSIONID);
+	bcopy(sessionid, nd->nd_sessionid, NFSX_V4SESSIONID);
 	tl += NFSX_V4SESSIONID / NFSX_UNSIGNED;
 	nd->nd_slotseq = tl;
 	if (error == 0) {
@@ -5593,6 +5595,7 @@ nfsrpc_destroysession(struct nfsmount *nmp, struct nfsclsession *tsep,
 	    0, NULL);
 	NFSM_BUILD(tl, uint32_t *, NFSX_V4SESSIONID);
 	bcopy(tsep->nfsess_sessionid, tl, NFSX_V4SESSIONID);
+	bcopy(tsep->nfsess_sessionid, nd->nd_sessionid, NFSX_V4SESSIONID);
 	nd->nd_flag |= ND_USEGSSNAME;
 	error = newnfs_request(nd, nmp, NULL, &nmp->nm_sockreq, NULL, p, cred,
 	    NFS_PROG, NFS_VER4, NULL, 1, NULL, NULL);