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libblkid/minix: Use same checks for version 3 

fsck.minix performs the same sanity checks on all versions of the
superblock. Update the probe to perform the same sanity checks so it is
less likely a different type of filesystem will be identified as minix.

Signed-off-by: Nate Clark <nate@neworld.us>
This commit is contained in:
Nate Clark 2017-01-04 15:24:32 -05:00
parent a9975c1072
commit f82c804869
1 changed files with 23 additions and 14 deletions
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37
libblkid/src/superblocks/minix.c
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@ -87,14 +87,12 @@ static int probe_minix(blkid_probe pr,
if (version < 1)
return 1;
unsigned long zones, ninodes, imaps, zmaps;
off_t firstz;
size_t zone_size;
if (version <= 2) {
struct minix_super_block *sb = (struct minix_super_block *) data;
unsigned long zones, ninodes, imaps, zmaps;
off_t firstz;
if (sb->s_imap_blocks == 0 || sb->s_zmap_blocks == 0 ||
sb->s_log_zone_size != 0)
return 1;
zones = version == 2 ? minix_swab32(swabme, sb->s_zones) :
minix_swab16(swabme, sb->s_nzones);
@ -102,19 +100,30 @@ static int probe_minix(blkid_probe pr,
imaps = minix_swab16(swabme, sb->s_imap_blocks);
zmaps = minix_swab16(swabme, sb->s_zmap_blocks);
firstz = minix_swab16(swabme, sb->s_firstdatazone);
/* sanity checks to be sure that the FS is really minix */
if (imaps * MINIX_BLOCK_SIZE * 8 < ninodes + 1)
return 1;
if (zmaps * MINIX_BLOCK_SIZE * 8 < zones - firstz + 1)
return 1;
zone_size = sb->s_log_zone_size;
} else if (version == 3) {
struct minix3_super_block *sb = (struct minix3_super_block *) data;
if (sb->s_imap_blocks == 0 || sb->s_zmap_blocks == 0)
return 1;
zones = minix_swab32(swabme, sb->s_zones);
ninodes = minix_swab32(swabme, sb->s_ninodes);
imaps = minix_swab16(swabme, sb->s_imap_blocks);
zmaps = minix_swab16(swabme, sb->s_zmap_blocks);
firstz = minix_swab16(swabme, sb->s_firstdatazone);
zone_size = sb->s_log_zone_size;
}
/* sanity checks to be sure that the FS is really minix.
* see disk-utils/fsck.minix.c read_superblock
*/
if (zone_size != 0 || ninodes == 0 || ninodes == UINT32_MAX)
return 1;
if (imaps * MINIX_BLOCK_SIZE * 8 < ninodes + 1)
return 1;
if (firstz > (off_t) zones)
return 1;
if (zmaps * MINIX_BLOCK_SIZE * 8 < zones - firstz + 1)
return 1;
/* unfortunately, some parts of ext3 is sometimes possible to
* interpreted as minix superblock. So check for extN magic
* string. (For extN magic string and offsets see ext.c.)