On Sat, 14 Jul 2007 03:47:21 +0400 Kirill Kuvaldin <kuvkir@xxxxxxxxx> wrote: > It turned out that mounting a corrupted ISO image to a regular file may > succeed, e.g. if an image was prepared as follows: > > $ dd if=correct.iso of=bad.iso bs=4k count=8 > > We then can mount it to a regular file: > > # mount -o loop -t iso9660 bad.iso /tmp/file > > But mounting it to a directory fails with -ENOTDIR, simply because > the root directory inode doesn't have S_IFDIR set and the condition > in graft_tree() is met: > > if (S_ISDIR(nd->dentry->d_inode->i_mode) != > S_ISDIR(mnt->mnt_root->d_inode->i_mode)) > return -ENOTDIR > > This is because the root directory inode was read from an incorrect > block. It's supposed to be read from sbi->s_firstdatazone, which is > an absolute value and gets messed up in the case of an incorrect image. > > In order to somehow circumvent this we have to check that the root > directory inode is actually a directory after all. > > > Signed-off-by: Kirill Kuvaldin <kuvkir@xxxxxxxxx> > > diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c > index 5c3eecf..ce5062a 100644 > --- a/fs/isofs/inode.c > +++ b/fs/isofs/inode.c > @@ -840,6 +840,15 @@ root_found: > goto out_no_root; > if (!inode->i_op) > goto out_bad_root; > + > + /* Make sure the root inode is a directory */ > + if (!S_ISDIR(inode->i_mode)) { > + printk(KERN_WARNING > + "isofs_fill_super: root inode is not a directory. " > + "Corrupted media?\n"); > + goto out_iput; > + } > + > /* get the root dentry */ > s->s_root = d_alloc_root(inode); > if (!(s->s_root)) I don't think any (all?) other filesystems perform checks like this. Is this something which can/should be performed at the VFS level? - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html