Re: [PATCH 4.4 106/124] netlink: Do not subscribe to non-existent groups
From: David Miller
Date: Sat Aug 04 2018 - 20:08:04 EST
From: Dmitry Safonov <dima@xxxxxxxxxx>
Date: Sun, 05 Aug 2018 00:44:28 +0100
> On Sat, 2018-08-04 at 16:33 -0700, David Miller wrote:
>> From: Dmitry Safonov <dima@xxxxxxxxxx>
>> Date: Sun, 05 Aug 2018 00:26:38 +0100
>> > Thanks for the testing, sorry again for the breakage.
>> > Will send the patch shortly (with sizeof(unsigned long long)
>> instead of
>> > hard-coded 64). Hopefully, not too late.
>> 'groups' is "long unsigned int" not "unsigned long long"
>> long unsigned int groups = nladdr->nl_groups;
>> And nladdr->nl_groups is specified as "__u32"
>> So the size of the relevant bits is actually strictly 32-bit.
>> This makes also the "ULL" in your constant specification incorrect as
>> So much crazy stuff going on here :-/
> Right, I misslooked that..
> How does this work on Android then?
> I doubt they changed uabi.
We can have many more than 32 multicast group subscriptions.
That's why the memberships are also stored in the nlk->groups array.
I'm --><--- this close to simply reverting all of your changes, the
missed masking seems to be quite harmless.