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| author | Theodore Ts'o <tytso@mit.edu> | 2008-08-23 22:11:01 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2008-08-24 17:24:18 -0400 |
| commit | 78d89cda680498957e4ad78602751d1f905cee08 (patch) | |
| tree | be9842075ca80de6227635950945a6b316eb59ed /lib/blkid | |
| parent | 30ab7f4c65bd32a7d24f53e8c87ed5b5ae757626 (diff) | |
| download | e2fsprogs-78d89cda680498957e4ad78602751d1f905cee08.tar.gz | |
libblkid: Fix false detection of DFSee created filesystems.
OS/2 and DFSee creates a pseudo FAT-12/16 header in the first 512
bytes of a filesystem which looks enough like a FAT-12/16 to fool
blkid. Part of this is because we don't require ms_magic or vs_magic
to be the strings "FAT12 ", "FAT16 ", or "FAT32 ", since some FAT
filesystem formatters don't set ms_magic or vs_magic. To address
this, we explicitly test for "JFS " and "HPFS " in ms_magic,
and if they are found, we assume the filesystem is definitely not
a FAT filesystem.
Addresses-Launchpad-Bug: #255255
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'lib/blkid')
| -rw-r--r-- | lib/blkid/probe.c | 27 |
1 files changed, 20 insertions, 7 deletions
diff --git a/lib/blkid/probe.c b/lib/blkid/probe.c index e2d8a257..225116a4 100644 --- a/lib/blkid/probe.c +++ b/lib/blkid/probe.c @@ -566,25 +566,38 @@ static int probe_fat_nomagic(struct blkid_probe *probe, struct blkid_magic *id __BLKID_ATTR((unused)), unsigned char *buf) { - struct vfat_super_block *vs; + struct msdos_super_block *ms; - vs = (struct vfat_super_block *)buf; + ms = (struct msdos_super_block *)buf; /* heads check */ - if (vs->vs_heads == 0) + if (ms->ms_heads == 0) return 1; /* cluster size check*/ - if (vs->vs_cluster_size == 0 || - (vs->vs_cluster_size & (vs->vs_cluster_size-1))) + if (ms->ms_cluster_size == 0 || + (ms->ms_cluster_size & (ms->ms_cluster_size-1))) return 1; /* media check */ - if (vs->vs_media < 0xf8 && vs->vs_media != 0xf0) + if (ms->ms_media < 0xf8 && ms->ms_media != 0xf0) return 1; /* fat counts(Linux kernel expects at least 1 FAT table) */ - if (!vs->vs_fats) + if (!ms->ms_fats) + return 1; + + /* + * OS/2 and apparently DFSee will place a FAT12/16-like + * pseudo-superblock in the first 512 bytes of non-FAT + * filesystems --- at least JFS and HPFS, and possibly others. + * So we explicitly check for those filesystems at the + * FAT12/16 filesystem magic field identifier, and if they are + * present, we rule this out as a FAT filesystem, despite the + * FAT-like pseudo-header. + */ + if ((memcmp(ms->ms_magic, "JFS ", 8) == 0) || + (memcmp(ms->ms_magic, "HPFS ", 8) == 0)) return 1; return probe_fat(probe, id, buf); |