Module Name: src
Committed By: christos
Date: Mon Jul 7 17:55:53 UTC 2014
Modified Files:
src/sbin/fsck_msdos: fat.c
Log Message:
From: http://marc.info/?l=openbsd-tech&m=140275150804337&w=2
Avoid infinite loops in cluster chain linked lists.
To generate a diff of this commit:
cvs rdiff -u -r1.25 -r1.26 src/sbin/fsck_msdos/fat.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sbin/fsck_msdos/fat.c
diff -u src/sbin/fsck_msdos/fat.c:1.25 src/sbin/fsck_msdos/fat.c:1.26
--- src/sbin/fsck_msdos/fat.c:1.25 Mon Jul 7 13:45:42 2014
+++ src/sbin/fsck_msdos/fat.c Mon Jul 7 13:55:53 2014
@@ -1,4 +1,4 @@
-/* $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
@@ -28,7 +28,7 @@
#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>
@@ -413,10 +413,10 @@ checkfat(struct bootblock *boot, struct
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;
@@ -424,14 +424,20 @@ checkfat(struct bootblock *boot, struct
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);
- ret |= tryclear(boot, fat, head, &fat[p].next);
- continue;
+ head, n);
+ goto clear;
+ }
+ 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);
