On Tue, Jul 21, 2020 at 06:16:27PM +0100, Al Viro wrote:
> On Tue, Jul 21, 2020 at 09:49:17AM -0700, Linus Torvalds wrote:
> > On Tue, Jul 21, 2020 at 9:28 AM Christoph Hellwig <hch@xxxxxx> wrote:
> > >
> > > +
> > > + /* traverse into overmounted root and then chroot to it */
> > > + if (!kern_path("/..", LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path) &&
> > > + !inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR) &&
> > > + ns_capable(current_user_ns(), CAP_SYS_CHROOT) &&
> > > + !security_path_chroot(&path)) {
> > > + set_fs_pwd(current->fs, &path);
> > > + set_fs_root(current->fs, &path);
> > > + }
> > > + path_put(&path);
> >
> > This looks wrong.
>
> It is wrong. kern_path() leaves *path unmodified in case of error, and
> that struct path is uninitialized here.
Yep. Only saving grace is that the error just doesn't happen during
early init.
