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Add more sanity checks for BPB parameters. Handle FAT12 format for media

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with sectors >= 32kByte.

Does fix PR 52485.
This commit is contained in:
mlelstv 2017-08-20 11:48:15 +00:00
parent 67b98d8500
commit 5815ca8f4d
1 changed files with 36 additions and 7 deletions
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43
sys/fs/msdosfs/msdosfs_vfsops.c
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@ -1,4 +1,4 @@
/* $NetBSD: msdosfs_vfsops.c,v 1.127 2017/04/17 08:32:00 hannken Exp $ */
/* $NetBSD: msdosfs_vfsops.c,v 1.128 2017/08/20 11:48:15 mlelstv Exp $ */
/*-
* Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
@ -48,7 +48,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: msdosfs_vfsops.c,v 1.127 2017/04/17 08:32:00 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: msdosfs_vfsops.c,v 1.128 2017/08/20 11:48:15 mlelstv Exp $");
#if defined(_KERNEL_OPT)
#include "opt_compat_netbsd.h"
@ -467,6 +467,7 @@ msdosfs_mountfs(struct vnode *devvp, struct mount *mp, struct lwp *l, struct msd
int ronly, error, BlkPerSec;
uint64_t psize;
unsigned secsize;
u_long fatbytes, fatblocksecs;
/* Flush out any old buffers remaining from a previous use. */
if ((error = vinvalbuf(devvp, V_SAVE, l->l_cred, l, 0, 0)) != 0)
@ -710,12 +711,40 @@ msdosfs_mountfs(struct vnode *devvp, struct mount *mp, struct lwp *l, struct msd
pmp->pm_fatdiv = 1;
}
}
if (FAT12(pmp))
pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
else
pmp->pm_fatblocksize = MAXBSIZE;
pmp->pm_fatblocksec = pmp->pm_fatblocksize / pmp->pm_BytesPerSec;
/* validate cluster count against FAT */
if ((pmp->pm_maxcluster & pmp->pm_fatmask) != pmp->pm_maxcluster) {
DPRINTF("maxcluster %lu outside of mask %#lx\n",
pmp->pm_maxcluster, pmp->pm_fatmask);
error = EINVAL;
goto error_exit;
}
/* validate FAT size */
fatbytes = (pmp->pm_maxcluster+1) * pmp->pm_fatmult / pmp->pm_fatdiv;
fatblocksecs = howmany(fatbytes, pmp->pm_BytesPerSec);
if (pmp->pm_FATsecs != fatblocksecs) {
DPRINTF("FATsecs %lu != real %lu\n", pmp->pm_FATsecs,
fatblocksecs);
error = EINVAL;
goto error_exit;
}
if (FAT12(pmp)) {
/*
* limit block size to what is needed to read a FAT block
* to not exceed MAXBSIZE
*/
pmp->pm_fatblocksec = min(3, fatblocksecs);
pmp->pm_fatblocksize = pmp->pm_fatblocksec
* pmp->pm_BytesPerSec;
} else {
pmp->pm_fatblocksize = MAXBSIZE;
pmp->pm_fatblocksec = pmp->pm_fatblocksize
/ pmp->pm_BytesPerSec;
}
pmp->pm_bnshift = ffs(pmp->pm_BytesPerSec) - 1;
/*