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From: http://marc.info/?l=openbsd-tech&m=140354518512871&w=2

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more consistency checks
This commit is contained in:
christos 2014-07-07 19:04:37 +00:00
parent d7660c3645
commit 0a21325ef0
1 changed files with 20 additions and 2 deletions
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22
sbin/fsck_msdos/boot.c
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@ -1,4 +1,3 @@
/* $NetBSD: boot.c,v 1.15 2009/04/11 07:14:50 lukem Exp $ */
/*
* Copyright (C) 1995, 1997 Wolfgang Solfrank
@ -28,11 +27,12 @@
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: boot.c,v 1.15 2009/04/11 07:14:50 lukem Exp $");
__RCSID("$NetBSD: boot.c,v 1.16 2014/07/07 19:04:37 christos Exp $");
#endif /* not lint */
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <stdio.h>
#include <unistd.h>
@ -64,8 +64,16 @@ readboot(int dosfs, struct bootblock *boot)
/* decode bios parameter block */
boot->BytesPerSec = block[11] + (block[12] << 8);
boot->SecPerClust = block[13];
if (boot->SecPerClust == 0 || popcount(boot->SecPerClust) != 1) {
pfatal("Invalid cluster size: %u\n", boot->SecPerClust);
return FSFATAL;
}
boot->ResSectors = block[14] + (block[15] << 8);
boot->FATs = block[16];
if (boot->FATs == 0) {
pfatal("Invalid number of FATs: %u\n", boot->FATs);
return FSFATAL;
}
boot->RootDirEnts = block[17] + (block[18] << 8);
boot->Sectors = block[19] + (block[20] << 8);
boot->Media = block[21];
@ -171,6 +179,10 @@ readboot(int dosfs, struct bootblock *boot)
}
/* Check backup FSInfo? XXX */
}
if (boot->FATsecs == 0) {
pfatal("Invalid number of FAT sectors: %u\n", boot->FATsecs);
return FSFATAL;
}
boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1)
/ boot->BytesPerSec
@ -193,6 +205,12 @@ readboot(int dosfs, struct bootblock *boot)
boot->NumSectors = boot->HugeSectors;
boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust;
if (boot->ClusterOffset > boot->NumSectors) {
pfatal("Cluster offset too large (%u clusters)\n",
boot->ClusterOffset);
return FSFATAL;
}
if (boot->flags&FAT32)
boot->ClustMask = CLUST32_MASK;
else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK))