From: "Bjørn Mork" <bjorn@mork•no>
To: Johannes Berg <johannes@sipsolutions•net>
Cc: netdev@vger•kernel.org, Jeff Layton <jeff.layton@primarydata•com>,
Sedat Dilek <sedat.dilek@gmail•com>
Subject: Re: [PATCH v3 2/3] genetlink: disallow subscribing to unknown mcast groups
Date: Wed, 04 Feb 2015 16:55:42 +0100 [thread overview]
Message-ID: <874mr1isch.fsf@nemi.mork.no> (raw)
In-Reply-To: <1423064608.4741.6.camel@sipsolutions.net> (Johannes Berg's message of "Wed, 04 Feb 2015 16:43:28 +0100")
Johannes Berg <johannes@sipsolutions•net> writes:
> On Wed, 2015-02-04 at 16:36 +0100, Bjørn Mork wrote:
>
>> >> - int i, err = 0;
>> >> + int i, err = -ENOENT;
>> >>
>> >> down_read(&cb_lock);
>> >> for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
>> >
>> > This change cause serious problems for acpid, as reported on
>> > https://bugzilla.kernel.org/show_bug.cgi?id=92121
>>
>> Ah, I see this bug is already fixed by commit 8b7c36d810c6 ("netlink:
>> fix wrong subscription bitmask to group mapping in"). Your change was
>> obviously correct, and found the long standing off by one bug. Thanks.
>>
>> Sorry about the noise. I should have checked the current "net" first.
>
> Interesting. I was completely willing to entertain the notion that some
> userspace might be broken and be attempting to subscribe to a (static
> through the hacks we had to put in or "I think I know it already")
> group.
Me to. So I went through the whole loop, checking that acpid did
everything by the book, adding a debug message to genl_bind() only to
see that it was called with '1' instead of the expected '2'. Then
looking at af_netlink.c and its history. Etc.
> Have you checked acpid with the bitmap fix?
No, not yet. But I went down far enough into this that I actually wrote
the exact same patch as Pablo. Had to scratch my head when I couldn't
cherry-pick it into net because it was already there :-)
So I am pretty sure Pablo's patch fixes the problem.
This was never noticed before because there are only two users,
netfilter and generic netlink, and both were willing to accept the
off-by-one values without much fuzz.
Bjørn
next prev parent reply other threads:[~2015-02-04 15:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-16 10:37 [PATCH v3 1/3] genetlink: document parallel_ops Johannes Berg
2015-01-16 10:37 ` [PATCH v3 2/3] genetlink: disallow subscribing to unknown mcast groups Johannes Berg
2015-01-16 22:20 ` David Miller
2015-02-04 11:55 ` Bjørn Mork
2015-02-04 15:36 ` Bjørn Mork
2015-02-04 15:43 ` Johannes Berg
2015-02-04 15:55 ` Bjørn Mork [this message]
2015-02-04 16:15 ` Bjørn Mork
2015-02-04 16:16 ` Johannes Berg
2015-01-16 10:37 ` [PATCH v3 3/3] genetlink: synchronize socket closing and family removal Johannes Berg
2015-01-16 22:20 ` David Miller
2015-01-16 22:19 ` [PATCH v3 1/3] genetlink: document parallel_ops David Miller
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