Messages in this thread Patch in this message | | | Date | Wed, 10 Sep 2008 08:33:24 -0400 | From | Bob Copeland <> | Subject | Re: __getblk infinite loop |
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On Fri, Sep 05, 2008 at 11:20:17AM +0200, Eric Sesterhenn wrote: > > Yes, it's always a case of garbage in, garbage out (or nothing out, as > > the case may be). > > > > No, it's not particularly programmer-friendly behaviour. > > Wouldnt it make sense to limit the loop in __getblk_slow()?
Back on this again, some patch like the following helps, but not enough because s_num_blocks could also be wrong (and is in the case of the fuzzed image #138). Unfortunately mounting a device where FS blocks > actual disk blocks is actually a handy use case.
I'm sure I'm showing my profound ignorance, but couldn't the address_ops of the loop device reject mapping the buffer since it knows it's outside the gendisk size?
NOT for applying:
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.
--- fs/omfs/dir.c | 22 ++++++++-------------- fs/omfs/file.c | 8 ++++---- fs/omfs/inode.c | 27 ++++++++++++++++----------- fs/omfs/omfs.h | 1 + 4 files changed, 29 insertions(+), 29 deletions(-)
diff --git a/fs/omfs/dir.c b/fs/omfs/dir.c index c0757e9..35fca1f 100644 --- a/fs/omfs/dir.c +++ b/fs/omfs/dir.c @@ -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, @@ -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; @@ -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; @@ -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; @@ -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; @@ -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; @@ -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; @@ -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; diff --git a/fs/omfs/file.c b/fs/omfs/file.c index 834b233..8719161 100644 --- a/fs/omfs/file.c +++ b/fs/omfs/file.c @@ -65,7 +65,7 @@ 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; @@ -105,7 +105,7 @@ 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]); @@ -247,7 +247,7 @@ 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; @@ -280,7 +280,7 @@ 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]); diff --git a/fs/omfs/inode.c b/fs/omfs/inode.c index d29047b..447d534 100644 --- a/fs/omfs/inode.c +++ b/fs/omfs/inode.c @@ -18,6 +18,15 @@ 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; @@ -95,15 +104,13 @@ 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; @@ -142,8 +149,7 @@ 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; @@ -190,7 +196,6 @@ 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; @@ -201,8 +206,7 @@ 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; @@ -311,6 +315,9 @@ 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++); @@ -409,7 +416,6 @@ 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); @@ -478,8 +484,7 @@ 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; diff --git a/fs/omfs/omfs.h b/fs/omfs/omfs.h index 2bc0f06..f043a67 100644 --- a/fs/omfs/omfs.h +++ b/fs/omfs/omfs.h @@ -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); -- 1.5.4.2.182.gb3092
-- Bob Copeland %% www.bobcopeland.com
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