From fac8422a41e61847acd06f7dab9fab9cfc2f4a74 Mon Sep 17 00:00:00 2001
From: Rick Macklem <rmacklem@FreeBSD.org>
Date: Sat, 4 Dec 2021 14:18:48 -0800
Subject: [PATCH] nfsd: Sanity check the Layouttype count

PR:	260155

(cherry picked from commit 480be96e1e24617f0f152256d7453f60774fd1f3)
---
 sys/fs/nfs/nfs_commonsubs.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sys/fs/nfs/nfs_commonsubs.c b/sys/fs/nfs/nfs_commonsubs.c
index 29e33372e83..5a944ffa8c1 100644
--- a/sys/fs/nfs/nfs_commonsubs.c
+++ b/sys/fs/nfs/nfs_commonsubs.c
@@ -2186,6 +2186,15 @@ nfsv4_loadattr(struct nfsrv_descript *nd, vnode_t vp,
 			NFSM_DISSECT(tl, u_int32_t *, NFSX_UNSIGNED);
 			attrsum += NFSX_UNSIGNED;
 			i = fxdr_unsigned(int, *tl);
+			/*
+			 * The RFCs do not define an upper limit for the
+			 * number of layout types, but 32 should be more
+			 * than enough.
+			 */
+			if (i < 0 || i > 32) {
+				error = NFSERR_BADXDR;
+				goto nfsmout;
+			}
 			if (i > 0) {
 				NFSM_DISSECT(tl, u_int32_t *, i *
 				    NFSX_UNSIGNED);