On Mon, Apr 02, 2018 at 03:30:56PM -0500, Eric W. Biederman wrote:
> Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> writes:
> > I don't think this is a dup of existing bug.
> > We need to fix either 9ee332d99e4d5a97 or d91ee87d8d85a080.
>
> Even if expanding mount_ns to more filesystems was magically fixed,
> proc would still have this issue with the pid namespace rather than
> the net namespace.
>
> This is a mess. I will take a look and see if I can see a a fix.
It's trivially fixable, and there's no need to modify mount_ns() at
all.
All we need is for rpc_kill_sb() to recognize whether we are already
through the point in rpc_fill_super() where the refcount is bumped.
That's it.
The most trivial way to do that is to move
net = get_net(sb->s_fs_info);
past
if (!root)
return -ENOMEM;
in the latter and have
out:
if (!sb->s_root)
net = NULL;
kill_litter_super(sb);
if (net)
put_net(net);
in the end of the former. And similar changes in other affected
instances.
