omfs: check bounds on block numbers before passing to sb_bread

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>

diff --git a/fs/omfs/dir.c b/fs/omfs/dir.c
index b42d624..393f3f6 100644 (file)
--- 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 6e7a329..76bc21b 100644 (file)
--- a/fs/omfs/file.c
+++ b/fs/omfs/file.c
@@ -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;
 
@@ -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]);
@@ -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;
 
@@ -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]);

diff --git a/fs/omfs/inode.c b/fs/omfs/inode.c
index b5d6380..bd4bf75 100644 (file)
--- a/fs/omfs/inode.c
+++ b/fs/omfs/inode.c
@@ -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;
@@ -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;
 
@@ -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;
 
@@ -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;
@@ -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;
 
@@ -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++);
@@ -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);
@@ -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;
 

diff --git a/fs/omfs/omfs.h b/fs/omfs/omfs.h
index ebe2fdb..7d414fe 100644 (file)
--- 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);