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>

4 files changed, 29 insertions, 29 deletions

diff --git a/fs/omfs/dir.c b/fs/omfs/dir.c
index b42d62419034..393f3f659da7 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 6e7a3291bbe8..76bc21b91a8a 100644
--- 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 b5d6380e03fb..bd4bf753a63b 100644
--- 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 ebe2fdbe535e..7d414fef501a 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);