Code: nfsd4_encode_layoutget(struct nfsd4_compoundres *resp, __be32 nfserr,
 		struct nfsd4_layoutget *lgp)
 {
 	struct xdr_stream *xdr = &resp->xdr;
	const struct nfsd4_layout_ops *ops =
		nfsd4_layout_ops[lgp->lg_layout_type];
 	__be32 *p;
 
 	dprintk("%s: err %d\n", __func__, nfserr);
	if (nfserr)
		goto out;

	nfserr = nfserr_resource;
	p = xdr_reserve_space(xdr, 36 + sizeof(stateid_opaque_t));
	if (!p)
		goto out;

	*p++ = cpu_to_be32(1);	/* we always set return-on-close */
	*p++ = cpu_to_be32(lgp->lg_sid.si_generation);
	p = xdr_encode_opaque_fixed(p, &lgp->lg_sid.si_opaque,
				    sizeof(stateid_opaque_t));

	*p++ = cpu_to_be32(1);	/* we always return a single layout */
	p = xdr_encode_hyper(p, lgp->lg_seg.offset);
	p = xdr_encode_hyper(p, lgp->lg_seg.length);
 	*p++ = cpu_to_be32(lgp->lg_seg.iomode);
 	*p++ = cpu_to_be32(lgp->lg_layout_type);
 
 	nfserr = ops->encode_layoutget(xdr, lgp);
 out:
 	kfree(lgp->lg_content);
	return nfserr;
}

Vulnerability Type: DoS 
CWE ID: CWE-404
Summary: The NFSv4 implementation in the Linux kernel through 4.11.1 allows local users to cause a denial of service (resource consumption) by leveraging improper channel callback shutdown when unmounting an NFSv4 filesystem, aka a *module reference and kernel daemon* leak.
Commit Message: Merge tag 'nfsd-4.12' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "Another RDMA update from Chuck Lever, and a bunch of miscellaneous
  bugfixes"

* tag 'nfsd-4.12' of git://linux-nfs.org/~bfields/linux: (26 commits)
  nfsd: Fix up the "supattr_exclcreat" attributes
  nfsd: encoders mustn't use unitialized values in error cases
  nfsd: fix undefined behavior in nfsd4_layout_verify
  lockd: fix lockd shutdown race
  NFSv4: Fix callback server shutdown
  SUNRPC: Refactor svc_set_num_threads()
  NFSv4.x/callback: Create the callback service through svc_create_pooled
  lockd: remove redundant check on block
  svcrdma: Clean out old XDR encoders
  svcrdma: Remove the req_map cache
  svcrdma: Remove unused RDMA Write completion handler
  svcrdma: Reduce size of sge array in struct svc_rdma_op_ctxt
  svcrdma: Clean up RPC-over-RDMA backchannel reply processing
  svcrdma: Report Write/Reply chunk overruns
  svcrdma: Clean up RDMA_ERROR path
  svcrdma: Use rdma_rw API in RPC reply path
  svcrdma: Introduce local rdma_rw API helpers
  svcrdma: Clean up svc_rdma_get_inv_rkey()
  svcrdma: Add helper to save pages under I/O
  svcrdma: Eliminate RPCRDMA_SQ_DEPTH_MULT
  ...