From ed0879d94420e960e137a683a4f2758d52ed3196 Mon Sep 17 00:00:00 2001
From: Xin LI <delphij@FreeBSD.org>
Date: Sat, 11 Jan 2020 03:59:06 +0000
Subject: [PATCH] Require FAT to occupy at least one sector.

Obtained from:	Android https://r.android.com/1205830
MFC after:	3 days
---
 sbin/fsck_msdosfs/boot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sbin/fsck_msdosfs/boot.c b/sbin/fsck_msdosfs/boot.c
index a3ba7abccb9..5f5fb24b117 100644
--- a/sbin/fsck_msdosfs/boot.c
+++ b/sbin/fsck_msdosfs/boot.c
@@ -250,7 +250,7 @@ readboot(int dosfs, struct bootblock *boot)
 		boot->FATsecs = boot->bpbFATsmall;
 	}
 
-	if (boot->FATsecs > UINT32_MAX / boot->bpbFATs) {
+	if (boot->FATsecs < 1 || boot->FATsecs > UINT32_MAX / boot->bpbFATs) {
 		pfatal("Invalid FATs(%u) with FATsecs(%zu)",
 			boot->bpbFATs, (size_t)boot->FATsecs);
 		return FSFATAL;