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

On Thu, Aug 30, 2018 at 01:54:48PM +0200, Arnd Bergmann wrote:

On Thu, Aug 30, 2018 at 1:04 PM Guillaume Nault [off-list ref] wrote:

quoted

On Wed, Aug 29, 2018 at 04:03:26PM +0200, Arnd Bergmann wrote:

quoted

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 <redacted>

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.

Sounds good. Thanks.