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MFC r268632:

Browse Source 
fsck_msdosfs: Assorted fixes from other BSDs.

When truncating cluster chains fix the length of the cluster head.
http://marc.info/?t=140304310700005&r=1&w=2

Avoid infinite loops in cluster chain linked lists.
http://marc.info/?l=openbsd-tech&m=140275150804337&w=2

Avoid off-by-one on FAT12 filesystems.
http://marc.info/?l=openbsd-tech&m=140234174104724&w=2

Obtained from:	NetBSD (from OpenBSD)
This commit is contained in:
pfg 2014-07-21 23:23:20 +00:00
parent 7dbe20dfe1
commit 1a6840cdce
2 changed files with 33 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
sbin/fsck_msdosfs/dir.c
View File

@ -419,13 +419,14 @@ checksize(struct bootblock *boot, struct fatEntry *fat, u_char *p,
fullpath(dir));
if (ask(1, "Drop superfluous clusters")) {
cl_t cl;
u_int32_t sz = 0;
u_int32_t sz, len;
for (cl = dir->head; (sz += boot->ClusterSize) <
dir->size;)
for (cl = dir->head, len = sz = 0;
(sz += boot->ClusterSize) < dir->size; len++)
cl = fat[cl].next;
clearchain(boot, fat, fat[cl].next);
fat[cl].next = CLUST_EOF;
fat[dir->head].length = len;
return FSFATMOD;
} else
return FSERROR;

41
sbin/fsck_msdosfs/fat.c
View File

@ -436,7 +436,15 @@ tryclear(struct bootblock *boot, struct fatEntry *fat, cl_t head, cl_t *truncp)
clearchain(boot, fat, head);
return FSFATMOD;
} else if (ask(0, "Truncate")) {
uint32_t len;
cl_t p;
for (p = head, len = 0;
p >= CLUST_FIRST && p < boot->NumClusters;
p = fat[p].next, len++)
continue;
*truncp = CLUST_EOF;
fat[head].length = len;
return FSFATMOD;
} else
return FSERROR;
@ -465,7 +473,8 @@ checkfat(struct bootblock *boot, struct fatEntry *fat)
/* follow the chain and mark all clusters on the way */
for (len = 0, p = head;
p >= CLUST_FIRST && p < boot->NumClusters;
p >= CLUST_FIRST && p < boot->NumClusters &&
fat[p].head != head;
p = fat[p].next) {
fat[p].head = head;
len++;
@ -486,10 +495,10 @@ checkfat(struct bootblock *boot, struct fatEntry *fat)
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;
@ -497,14 +506,20 @@ checkfat(struct bootblock *boot, struct fatEntry *fat)
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);
@ -621,13 +636,15 @@ writefat(int fs, struct bootblock *boot, struct fatEntry *fat, int correct_fat)
default:
if (fat[cl].next == CLUST_FREE)
boot->NumFree++;
if (cl + 1 < boot->NumClusters
&& fat[cl + 1].next == CLUST_FREE)
boot->NumFree++;
*p++ = (u_char)fat[cl].next;
*p++ = (u_char)((fat[cl].next >> 8) & 0xf)
|(u_char)(fat[cl+1].next << 4);
*p++ = (u_char)(fat[++cl].next >> 4);
*p = (u_char)((fat[cl].next >> 8) & 0xf);
cl++;
if (cl >= boot->NumClusters)
break;
if (fat[cl].next == CLUST_FREE)
boot->NumFree++;
*p++ |= (u_char)(fat[cl + 1].next << 4);
*p++ = (u_char)(fat[cl + 1].next >> 4);
break;
}
}