Re: [PATCH net-next 1/5] pppoe: fix PPPOEIOCSFWD compat handling

[Arnd Bergmann]

On Thu, Aug 30, 2018 at 1:04 PM Guillaume Nault <g.nault@xxxxxxxxxxxx> wrote:
>
> On Wed, Aug 29, 2018 at 04:03:26PM +0200, Arnd Bergmann wrote:
> > Support for handling the PPPOEIOCSFWD ioctl in compat mode was added in
> > linux-2.5.69 along with hundreds of other commands, but was always broken
> > sincen only the structure is compatible, but the command number is not,
> > due to the size being sizeof(size_t), or at first sizeof(sizeof((struct
> > sockaddr_pppox)), which is different on 64-bit architectures.
> >
> And the implementation was broken until 2016 (see 29e73269aa4d ("pppoe:
> fix reference counting in PPPoE proxy")), and nobody ever noticed. I
> should probably have removed this ioctl entirely instead of fixing it.
> Clearly, it has never been used.
>
> If you think it's worth fixing (as opposed to dropping this ioctl or
> its compat mode), then,
> Acked-by: Guillaume Nault <g.nault@xxxxxxxxxxxx>

I don't care much, but fixing it seems seems easier than coming
up with a convincing rationale for dropping.

I'll update the changelog text to include your additional background
information though, unless someone else prefers to have it dropped.

       Arnd