From 817794e0df5fea495396c18878804044436832be Mon Sep 17 00:00:00 2001 From: Kirill Kuvaldin Date: Tue, 31 Jul 2007 00:38:58 -0700 Subject: [PATCH] isofs: mounting to regular file may succeed 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/isofs/inode.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c index 95c72aa8186..043b470fd3b 100644 --- a/fs/isofs/inode.c +++ b/fs/isofs/inode.c @@ -846,6 +846,15 @@ 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)) -- 2.20.1