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V7: Adjust sanity checks for some volumes

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Newly mkfs-ed filesystems from Seventh Edition have last modification
time set to zero, but are otherwise perfectly valid.

Also, tighten up other sanity checks to filter out most filesystems with
different bytesex than we're using.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Lubomir Rintel 2010-07-22 03:11:48 +02:00 committed by Al Viro
parent b76212d7f1
commit 496ee9b8f3
2 changed files with 15 additions and 2 deletions
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6
fs/sysv/super.c
View File

@ -469,7 +469,7 @@ static int v7_fill_super(struct super_block *sb, void *data, int silent)
v7sb = (struct v7_super_block *) bh->b_data;
if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
fs32_to_cpu(sbi, v7sb->s_time) == 0)
fs32_to_cpu(sbi, v7sb->s_fsize) > V7_MAXSIZE)
goto failed;
/* plausibility check on root inode: it is a directory,
@ -479,7 +479,9 @@ static int v7_fill_super(struct super_block *sb, void *data, int silent)
v7i = (struct sysv_inode *)(bh2->b_data + 64);
if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
(fs32_to_cpu(sbi, v7i->i_size) == 0) ||
(fs32_to_cpu(sbi, v7i->i_size) & 017) != 0)
(fs32_to_cpu(sbi, v7i->i_size) & 017) ||
(fs32_to_cpu(sbi, v7i->i_size) > V7_NFILES *
sizeof (struct sysv_dir_entry)))
goto failed;
brelse(bh2);
bh2 = NULL;

11
include/linux/sysv_fs.h
View File

@ -148,6 +148,17 @@ struct v7_super_block {
char s_fname[6]; /* file system name */
char s_fpack[6]; /* file system pack name */
};
/* Constants to aid sanity checking */
/* This is not a hard limit, nor enforced by v7 kernel. It's actually just
* the limit used by Seventh Edition's ls, though is high enough to assume
* that no reasonable file system would have that much entries in root
* directory. Thus, if we see anything higher, we just probably got the
* endiannes wrong. */
#define V7_NFILES 1024
/* The disk addresses are three-byte (despite direct block addresses being
* aligned word-wise in inode). If the most significant byte is non-zero,
* something is most likely wrong (not a filesystem, bad bytesex). */
#define V7_MAXSIZE 0x00ffffff
/* Coherent super-block data on disk */
#define COH_NICINOD 100 /* number of inode cache entries */