Date: Mon, 9 Sep 2019 17:33:32 +0000 (UTC) From: Ed Maste <emaste@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: svn commit: r352080 - stable/12/usr.sbin/makefs/msdos Message-ID: <201909091733.x89HXW7F083410@repo.freebsd.org>
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Author: emaste Date: Mon Sep 9 17:33:31 2019 New Revision: 352080 URL: https://svnweb.freebsd.org/changeset/base/352080 Log: MFC r351347: makefs: Verify that the BPB media descriptor and FAT ID match From r322982 in sys/fs/msdosfs. Modified: stable/12/usr.sbin/makefs/msdos/msdosfs_fat.c Directory Properties: stable/12/ (props changed) Modified: stable/12/usr.sbin/makefs/msdos/msdosfs_fat.c ============================================================================== --- stable/12/usr.sbin/makefs/msdos/msdosfs_fat.c Mon Sep 9 17:32:40 2019 (r352079) +++ stable/12/usr.sbin/makefs/msdos/msdosfs_fat.c Mon Sep 9 17:33:31 2019 (r352080) @@ -888,19 +888,17 @@ fillinusemap(struct msdosfsmount *pmp) * zero. These represent free clusters. */ pmp->pm_freeclustercount = 0; - for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { + for (cn = 0; cn <= pmp->pm_maxcluster; cn++) { byteoffset = FATOFS(pmp, cn); bo = byteoffset % pmp->pm_fatblocksize; - if (bo == 0 || bp == NULL) { + if (bo == 0) { /* Read new FAT block */ if (bp != NULL) brelse(bp); fatblock(pmp, byteoffset, &bn, &bsize, NULL); error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); - if (error != 0) { - brelse(bp); + if (error != 0) return (error); - } } if (FAT32(pmp)) readcn = getulong(bp->b_data + bo); @@ -910,7 +908,19 @@ fillinusemap(struct msdosfsmount *pmp) readcn >>= 4; readcn &= pmp->pm_fatmask; - if (readcn == CLUST_FREE) + /* + * Check if the FAT ID matches the BPB's media descriptor and + * all other bits are set to 1. + */ + if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | + pmp->pm_bpb.bpbMedia)) { +#ifdef MSDOSFS_DEBUG + printf("mountmsdosfs(): Media descriptor in BPB" + "does not match FAT ID\n"); +#endif + brelse(bp); + return (EINVAL); + } else if (readcn == CLUST_FREE) usemap_free(pmp, cn); } if (bp != NULL)
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