NFSD: Remove argument length checking in nfsd_dispatch()

Now that the argument decoders for NFSv2 and NFSv3 use the
xdr_stream mechanism, the version-specific length checking logic in
nfsd_dispatch() is no longer necessary.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfssvc.c

@@ -955,37 +955,6 @@ nfsd(void *vrqstp)
 	return 0;
 }
 
-/*
- * A write procedure can have a large argument, and a read procedure can
- * have a large reply, but no NFSv2 or NFSv3 procedure has argument and
- * reply that can both be larger than a page.  The xdr code has taken
- * advantage of this assumption to be a sloppy about bounds checking in
- * some cases.  Pending a rewrite of the NFSv2/v3 xdr code to fix that
- * problem, we enforce these assumptions here:
- */
-static bool nfs_request_too_big(struct svc_rqst *rqstp,
-				const struct svc_procedure *proc)
-{
-	/*
-	 * The ACL code has more careful bounds-checking and is not
-	 * susceptible to this problem:
-	 */
-	if (rqstp->rq_prog != NFS_PROGRAM)
-		return false;
-	/*
-	 * Ditto NFSv4 (which can in theory have argument and reply both
-	 * more than a page):
-	 */
-	if (rqstp->rq_vers >= 4)
-		return false;
-	/* The reply will be small, we're OK: */
-	if (proc->pc_xdrressize > 0 &&
-	    proc->pc_xdrressize < XDR_QUADLEN(PAGE_SIZE))
-		return false;
-
-	return rqstp->rq_arg.len > PAGE_SIZE;
-}
-
 /**
  * nfsd_dispatch - Process an NFS or NFSACL Request
  * @rqstp: incoming request
@@ -1004,9 +973,6 @@ int nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
 	struct kvec *resv = &rqstp->rq_res.head[0];
 	__be32 *p;
 
-	if (nfs_request_too_big(rqstp, proc))
-		goto out_decode_err;
-
 	/*
 	 * Give the xdr decoder a chance to change this if it wants
 	 * (necessary in the NFSv4.0 compound case)