makefs: Verify that the BPB media descriptor and FAT ID match
From r322982 in sys/fs/msdosfs.
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parent
476b0ab758
commit
59e9b3695a
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=351347
@ -887,19 +887,17 @@ fillinusemap(struct msdosfsmount *pmp)
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* zero. These represent free clusters.
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*/
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pmp->pm_freeclustercount = 0;
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for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) {
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for (cn = 0; cn <= pmp->pm_maxcluster; cn++) {
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byteoffset = FATOFS(pmp, cn);
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bo = byteoffset % pmp->pm_fatblocksize;
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if (bo == 0 || bp == NULL) {
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if (bo == 0) {
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/* Read new FAT block */
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if (bp != NULL)
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brelse(bp);
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fatblock(pmp, byteoffset, &bn, &bsize, NULL);
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error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
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if (error != 0) {
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brelse(bp);
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if (error != 0)
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return (error);
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}
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}
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if (FAT32(pmp))
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readcn = getulong(bp->b_data + bo);
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@ -909,7 +907,19 @@ fillinusemap(struct msdosfsmount *pmp)
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readcn >>= 4;
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readcn &= pmp->pm_fatmask;
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if (readcn == CLUST_FREE)
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/*
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* Check if the FAT ID matches the BPB's media descriptor and
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* all other bits are set to 1.
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*/
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if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) |
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pmp->pm_bpb.bpbMedia)) {
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#ifdef MSDOSFS_DEBUG
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printf("mountmsdosfs(): Media descriptor in BPB"
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"does not match FAT ID\n");
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#endif
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brelse(bp);
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return (EINVAL);
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} else if (readcn == CLUST_FREE)
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usemap_free(pmp, cn);
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}
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if (bp != NULL)
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