Commit d6ddf554 authored Nov 16, 2006 by Eric Sandeen Committed by Linus Torvalds Nov 16, 2006

[PATCH] hfs_fill_super returns success even if no root inode

http://kernelfun.blogspot.com/2006/11/mokb-14-11-2006-linux-26x-selinux.html



mount that image...
fs: filesystem was not cleanly unmounted, running fsck.hfs is recommended.  mounting read-only.
hfs: get root inode failed.
BUG: unable to handle kernel NULL pointer dereference at virtual address 00000018
 printing eip
...
EIP is at superblock_doinit+0x21/0x767
...
 [] selinux_sb_kern_mount+0xc/0x4b
 [] vfs_kern_mount+0x99/0xf6
 [] do_kern_mount+0x2d/0x3e
 [] do_mount+0x5fa/0x66d
 [] sys_mount+0x77/0xae
 [] syscall_call+0x7/0xb
DWARF2 unwinder stuck at syscall_call+0x7/0xb

hfs_fill_super() returns success even if
  root_inode = hfs_iget(sb, &fd.search_key->cat, &rec);
or
  sb->s_root = d_alloc_root(root_inode);

fails.  This superblock finds its way to superblock_doinit() which does:

        struct dentry *root = sb->s_root;
        struct inode *inode = root->d_inode;

and boom.  Need to make sure the error cases return an error, I think.

[akpm@osdl.org: return -ENOMEM on oom]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 4c1b6d18

fs/hfs/super.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -390,11 +390,13 @@ static int hfs_fill_super(struct super_block sb, void data, int silent)
		hfs_find_exit(&fd);
		goto bail_no_root;
		}
		res = -EINVAL;
		root_inode = hfs_iget(sb, &fd.search_key->cat, &rec);
		hfs_find_exit(&fd);
		if (!root_inode)
		goto bail_no_root;

		res = -ENOMEM;
		sb->s_root = d_alloc_root(root_inode);
		if (!sb->s_root)
		goto bail_iput;

Admin message