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omfs: check bounds on block numbers before passing to sb_bread
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In case of filesystem corruption, passing unchecked block numbers into
sb_bread can result in an infinite loop in __getblk().  Introduce a wrapper
function omfs_sbread() to check the block numbers and to also perform the
clus_to_blk() scaling.

Signed-off-by: Bob Copeland <me@bobcopeland.com>
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Bob Copeland committed Jul 10, 2010
1 parent 70d9e38 commit f068272
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Showing 4 changed files with 29 additions and 29 deletions.
22 changes: 8 additions & 14 deletions fs/omfs/dir.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,11 +25,10 @@ static struct buffer_head *omfs_get_bucket(struct inode *dir,
const char *name, int namelen, int *ofs)
{
int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
int block = clus_to_blk(OMFS_SB(dir->i_sb), dir->i_ino);
int bucket = omfs_hash(name, namelen, nbuckets);

*ofs = OMFS_DIR_START + bucket * 8;
return sb_bread(dir->i_sb, block);
return omfs_bread(dir->i_sb, dir->i_ino);
}

static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
Expand All @@ -42,8 +41,7 @@ static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
*prev_block = ~0;

while (block != ~0) {
bh = sb_bread(dir->i_sb,
clus_to_blk(OMFS_SB(dir->i_sb), block));
bh = omfs_bread(dir->i_sb, block);
if (!bh) {
err = -EIO;
goto err;
Expand Down Expand Up @@ -86,11 +84,10 @@ static struct buffer_head *omfs_find_entry(struct inode *dir,
int omfs_make_empty(struct inode *inode, struct super_block *sb)
{
struct omfs_sb_info *sbi = OMFS_SB(sb);
int block = clus_to_blk(sbi, inode->i_ino);
struct buffer_head *bh;
struct omfs_inode *oi;

bh = sb_bread(sb, block);
bh = omfs_bread(sb, inode->i_ino);
if (!bh)
return -ENOMEM;

Expand Down Expand Up @@ -134,7 +131,7 @@ static int omfs_add_link(struct dentry *dentry, struct inode *inode)
brelse(bh);

/* now set the sibling and parent pointers on the new inode */
bh = sb_bread(dir->i_sb, clus_to_blk(OMFS_SB(dir->i_sb), inode->i_ino));
bh = omfs_bread(dir->i_sb, inode->i_ino);
if (!bh)
goto out;

Expand Down Expand Up @@ -190,8 +187,7 @@ static int omfs_delete_entry(struct dentry *dentry)
if (prev != ~0) {
/* found in middle of list, get list ptr */
brelse(bh);
bh = sb_bread(dir->i_sb,
clus_to_blk(OMFS_SB(dir->i_sb), prev));
bh = omfs_bread(dir->i_sb, prev);
if (!bh)
goto out;

Expand Down Expand Up @@ -224,8 +220,7 @@ static int omfs_dir_is_empty(struct inode *inode)
u64 *ptr;
int i;

bh = sb_bread(inode->i_sb, clus_to_blk(OMFS_SB(inode->i_sb),
inode->i_ino));
bh = omfs_bread(inode->i_sb, inode->i_ino);

if (!bh)
return 0;
Expand Down Expand Up @@ -353,8 +348,7 @@ static int omfs_fill_chain(struct file *filp, void *dirent, filldir_t filldir,

/* follow chain in this bucket */
while (fsblock != ~0) {
bh = sb_bread(dir->i_sb, clus_to_blk(OMFS_SB(dir->i_sb),
fsblock));
bh = omfs_bread(dir->i_sb, fsblock);
if (!bh)
goto out;

Expand Down Expand Up @@ -466,7 +460,7 @@ static int omfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
hchain = (filp->f_pos >> 20) - 1;
hindex = filp->f_pos & 0xfffff;

bh = sb_bread(dir->i_sb, clus_to_blk(OMFS_SB(dir->i_sb), dir->i_ino));
bh = omfs_bread(dir->i_sb, dir->i_ino);
if (!bh)
goto out;

Expand Down
8 changes: 4 additions & 4 deletions fs/omfs/file.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ int omfs_shrink_inode(struct inode *inode)
if (inode->i_size != 0)
goto out;

bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
bh = omfs_bread(inode->i_sb, next);
if (!bh)
goto out;

Expand Down Expand Up @@ -90,7 +90,7 @@ int omfs_shrink_inode(struct inode *inode)
if (next == ~0)
break;

bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
bh = omfs_bread(inode->i_sb, next);
if (!bh)
goto out;
oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
Expand Down Expand Up @@ -232,7 +232,7 @@ static int omfs_get_block(struct inode *inode, sector_t block,
int remain;

ret = -EIO;
bh = sb_bread(inode->i_sb, clus_to_blk(sbi, inode->i_ino));
bh = omfs_bread(inode->i_sb, inode->i_ino);
if (!bh)
goto out;

Expand Down Expand Up @@ -265,7 +265,7 @@ static int omfs_get_block(struct inode *inode, sector_t block,
break;

brelse(bh);
bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
bh = omfs_bread(inode->i_sb, next);
if (!bh)
goto out;
oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
Expand Down
27 changes: 16 additions & 11 deletions fs/omfs/inode.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,15 @@ MODULE_AUTHOR("Bob Copeland <me@bobcopeland.com>");
MODULE_DESCRIPTION("OMFS (ReplayTV/Karma) Filesystem for Linux");
MODULE_LICENSE("GPL");

struct buffer_head *omfs_bread(struct super_block *sb, sector_t block)
{
struct omfs_sb_info *sbi = OMFS_SB(sb);
if (block >= sbi->s_num_blocks)
return NULL;

return sb_bread(sb, clus_to_blk(sbi, block));
}

struct inode *omfs_new_inode(struct inode *dir, int mode)
{
struct inode *inode;
Expand Down Expand Up @@ -93,15 +102,13 @@ static int __omfs_write_inode(struct inode *inode, int wait)
struct omfs_inode *oi;
struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
struct buffer_head *bh, *bh2;
unsigned int block;
u64 ctime;
int i;
int ret = -EIO;
int sync_failed = 0;

/* get current inode since we may have written sibling ptrs etc. */
block = clus_to_blk(sbi, inode->i_ino);
bh = sb_bread(inode->i_sb, block);
bh = omfs_bread(inode->i_sb, inode->i_ino);
if (!bh)
goto out;

Expand Down Expand Up @@ -140,8 +147,7 @@ static int __omfs_write_inode(struct inode *inode, int wait)

/* if mirroring writes, copy to next fsblock */
for (i = 1; i < sbi->s_mirrors; i++) {
bh2 = sb_bread(inode->i_sb, block + i *
(sbi->s_blocksize / sbi->s_sys_blocksize));
bh2 = omfs_bread(inode->i_sb, inode->i_ino + i);
if (!bh2)
goto out_brelse;

Expand Down Expand Up @@ -193,7 +199,6 @@ struct inode *omfs_iget(struct super_block *sb, ino_t ino)
struct omfs_sb_info *sbi = OMFS_SB(sb);
struct omfs_inode *oi;
struct buffer_head *bh;
unsigned int block;
u64 ctime;
unsigned long nsecs;
struct inode *inode;
Expand All @@ -204,8 +209,7 @@ struct inode *omfs_iget(struct super_block *sb, ino_t ino)
if (!(inode->i_state & I_NEW))
return inode;

block = clus_to_blk(sbi, ino);
bh = sb_bread(inode->i_sb, block);
bh = omfs_bread(inode->i_sb, ino);
if (!bh)
goto iget_failed;

Expand Down Expand Up @@ -319,6 +323,9 @@ static int omfs_get_imap(struct super_block *sb)
goto nomem;

block = clus_to_blk(sbi, sbi->s_bitmap_ino);
if (block >= sbi->s_num_blocks)
goto nomem;

ptr = sbi->s_imap;
for (count = bitmap_size; count > 0; count -= sb->s_blocksize) {
bh = sb_bread(sb, block++);
Expand Down Expand Up @@ -417,7 +424,6 @@ static int omfs_fill_super(struct super_block *sb, void *data, int silent)
struct omfs_root_block *omfs_rb;
struct omfs_sb_info *sbi;
struct inode *root;
sector_t start;
int ret = -EINVAL;

save_mount_options(sb, (char *) data);
Expand Down Expand Up @@ -486,8 +492,7 @@ static int omfs_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_block_shift = get_bitmask_order(sbi->s_blocksize) -
get_bitmask_order(sbi->s_sys_blocksize);

start = clus_to_blk(sbi, be64_to_cpu(omfs_sb->s_root_block));
bh2 = sb_bread(sb, start);
bh2 = omfs_bread(sb, be64_to_cpu(omfs_sb->s_root_block));
if (!bh2)
goto out_brelse_bh;

Expand Down
1 change: 1 addition & 0 deletions fs/omfs/omfs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,7 @@ extern void omfs_make_empty_table(struct buffer_head *bh, int offset);
extern int omfs_shrink_inode(struct inode *inode);

/* inode.c */
extern struct buffer_head *omfs_bread(struct super_block *sb, sector_t block);
extern struct inode *omfs_iget(struct super_block *sb, ino_t inode);
extern struct inode *omfs_new_inode(struct inode *dir, int mode);
extern int omfs_reserve_block(struct super_block *sb, sector_t block);
Expand Down

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