 @@ -1,14 +1,14 @@
-/*	$NetBSD: fat.c,v 1.25 2014/07/07 17:45:42 christos Exp $	*/
+/*	$NetBSD: fat.c,v 1.26 2014/07/07 17:55:53 christos Exp $	*/
 /*
  * Copyright (C) 1995, 1996, 1997 Wolfgang Solfrank
  * Copyright (c) 1995 Martin Husemann
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
 @@ -18,27 +18,27 @@
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
 #ifndef lint
-__RCSID("$NetBSD: fat.c,v 1.25 2014/07/07 17:45:42 christos Exp $");
+__RCSID("$NetBSD: fat.c,v 1.26 2014/07/07 17:55:53 christos Exp $");
 #endif /* not lint */
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
 #include <stdio.h>
 #include <unistd.h>
 #include "ext.h"
 #include "fsutil.h"
 static int checkclnum(struct bootblock *, u_int, cl_t, cl_t *);
 static int clustdiffer(cl_t, cl_t *, cl_t *, u_int);
 @@ -403,45 +403,51 @@ checkfat(struct bootblock *boot, struct
+	}
 	/*
 	 * pass 2: check for crosslinked chains (we couldn't do this in pass 1 because
 	 * we didn't know the real start of the chain then - would have treated partial
 	 * chains as interlinked with their main chain)
 	 */
 	for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
 		/* find next untravelled chain */
 		if (fat[head].head != head)
 			continue;
 		/* follow the chain to its end (hopefully) */
-		for (p = head;
+		for (len = fat[head].length, p = head;
 		     (n = fat[p].next) >= CLUST_FIRST && n < boot->NumClusters;
 		     p = n)
-			if (fat[n].head != head)
+			if (fat[n].head != head || len-- < 2)
 				break;
 		if (n >= CLUST_EOFS)
 			continue;
 		if (n == CLUST_FREE || n >= CLUST_RSRVD) {
 			pwarn("Cluster chain starting at %u ends with cluster marked %s\n",
 			      head, rsrvdcltype(n));
 clear:
 			ret |= tryclear(boot, fat, head, &fat[p].next);
 			continue;
+		}
 		if (n < CLUST_FIRST || n >= boot->NumClusters) {
 			pwarn("Cluster chain starting at %u ends with cluster out of range (%u)\n",
-			      head, n);
+			    head, n);
-			ret |= tryclear(boot, fat, head, &fat[p].next);
+			goto clear;
 			continue;
 		if (head == fat[n].head) {
 			pwarn("Cluster chain starting at %u loops at cluster %u\n",
 			    head, p);
 			goto clear;
+		}
 		pwarn("Cluster chains starting at %u and %u are linked at cluster %u\n",
 		      head, fat[n].head, n);
 		conf = tryclear(boot, fat, head, &fat[p].next);
 		if (ask(0, "Clear chain starting at %u", h = fat[n].head)) {
 			if (conf == FSERROR) {
 				/*
 				 * Transfer the common chain to the one not cleared above.
 				 */
 				for (p = n;
 				     p >= CLUST_FIRST && p < boot->NumClusters;
 				     p = fat[p].next) {
 					if (h != fat[p].head) {