Re: [PATCH net 0/4] various compat ioctl fixes

[David Miller <davem@davemloft.net>]

From: Al Viro <viro@zeniv.linux.org.uk>
Date: Wed, 30 Jan 2019 15:40:09 +0000

> On Mon, Jan 28, 2019 at 10:32:30PM +0100, Johannes Berg wrote:
> 
>> At the same time, fixing all this _completely_ is not very realistic, it
>> would require passing the ifreq size through to lots of places and
>> making the user copy there take the size rather than sizeof(ifreq),
>> obviously the very least to the method decnet uses, i.e. sock->ioctl() I
>> think, but clearly that affects every other protocol too.
>> This was what my previous patch had done partially for the directly
>> handled ioctls (the revert of which is the first patch in this series).
>> 
>> > From what I can see this looks like probably the simplest way to
>> > fix this in net and -stable currently.
>> 
>> I tend to agree, at least to fix the regression.
>> 
>> We can still deliberate separately if we want to fix decnet for compat
>> or if nobody cares now. But perhaps better decnet broken (quite
>> obviously and detectably) like it basically always was, than IP broken
>> (subtly, if your struct ends up landing at the end of a page).
>> 
>> Al, care to speak up about this here?
> 
> Umm...  Short-term I don't see anything better; long-term I would really
> like to see compat_alloc_user_space()/copy_in_user() crap gone and
> copyin-copyout for anything more or less generic lifted up as far as
> cleanly possible, but let's not mix it with regression fixing.

It's a real shame, I thought it was a super clever solution to that
problem space at the time we added it.

> So for the lack of better short-term solutions,
> Acked-by: Al Viro <viro@zeniv.linux.org.uk>
> on the series.

Ok, series applied, thanks everyone.

I'll queue this up for -stable too.