Re: [PATCH v3] net: make get_net_ns return error if NET_NS is disabled

[Changbin Du <changbin.du@gmail.com>]

On Thu, Jun 10, 2021 at 10:51:12AM -0700, Jakub Kicinski wrote:
> On Thu, 10 Jun 2021 23:39:41 +0800 Changbin Du wrote:
> > There is a panic in socket ioctl cmd SIOCGSKNS when NET_NS is not enabled.
> > The reason is that nsfs tries to access ns->ops but the proc_ns_operations
> > is not implemented in this case.
> > 
> > [7.670023] Unable to handle kernel NULL pointer dereference at virtual address 00000010
> > [7.670268] pgd = 32b54000
> > [7.670544] [00000010] *pgd=00000000
> > [7.671861] Internal error: Oops: 5 [#1] SMP ARM
> > [7.672315] Modules linked in:
> > [7.672918] CPU: 0 PID: 1 Comm: systemd Not tainted 5.13.0-rc3-00375-g6799d4f2da49 #16
> > [7.673309] Hardware name: Generic DT based system
> > [7.673642] PC is at nsfs_evict+0x24/0x30
> > [7.674486] LR is at clear_inode+0x20/0x9c
> > 
> > The same to tun SIOCGSKNS command.
> > 
> > To fix this problem, we make get_net_ns() return -EINVAL when NET_NS is
> > disabled. Meanwhile move it to right place net/core/net_namespace.c.
> 
> I'm assuming you went from EOPNOTSUPP to EINVAL to follow what the
> existing helpers in the header do?
>
yes, make them behaviour in the same manner.

> Acked-by: Jakub Kicinski <kuba@kernel.org>
> 
> Thanks!

-- 
Cheers,
Changbin Du