Re: NEEDS FIXING - Was: Re: [PATCH v2] ipv4: ping: fix bind address validity check

From: Jakub Kicinski <kuba@kernel.org>
To: "Riccardo Paolo Bestetti" <pbl@bestov.io>
Cc: <davem@davemloft.net>, <cmllamas@google.com>,
	<yoshfuji@linux-ipv6.org>, <dsahern@kernel.org>,
	<edumazet@google.com>, <pabeni@redhat.com>,
	<kernel-team@android.com>, <linux-kernel@vger.kernel.org>,
	<netdev@vger.kernel.org>, <linmiaohe@huawei.com>
Subject: Re: NEEDS FIXING - Was: Re: [PATCH v2] ipv4: ping: fix bind address validity check
Date: Fri, 17 Jun 2022 19:58:16 -0700	[thread overview]
Message-ID: <20220617195816.53a2f2cf@kernel.org> (raw)
In-Reply-To: <CKSU5Q2M1IE3.39AS0HDHTZPN@enhorning>

On Sat, 18 Jun 2022 02:32:55 +0200 Riccardo Paolo Bestetti wrote:
> I receompiled the kernel from the net tree to do some more manual testing
> on the patch and I have two things to disclose. Sorry for the caps in
> the subject.
> 
> TL;DR: I noticed that one of the regressions tests is (correctly)
> failing, but for the wrong reasons; and the patch I sent contains a
> mistake, and unfortunately it has already been applied to the tree as
> commit b4a028c4d0.
> 
> Long version below.
> 
> 1) If you run regression tests with -v, the (correct -- see below) ICMP
> tests for broadcast and multicast binding do not fail with
> EADDRNOTAVAIL, but with ACCES, but only when run through fcnal-test.sh.
> This is also true for one of the additional (commented out) tests you
> can find in my patch following this email. I'm not sure why this
> happens; however I'm reasonably convinced it is a quirk or a consequence
> of the testing methodology/setup. Can anyone offer any insights?
> 
> 2) My patch is faulty. I had a complete and tested patch, including code
> fixing the regression. Instead of sending it, however, I decided to
> adapt it to preserve Carlos Llamas' version of ping.c, since they posted
> their patch first. In doing so I used a work branch which contained a
> faulty version (wrong flags) of the regression tests. The resulting
> faulty patch is, unfortunately, currently in the tree.
> 
> At this point, due to the unfortunate combination of (1) and (2), it
> might be worth reverting the patch altogether and just applying the v1
> (i.e. without the regression tests) to the tree and to the relevant LTS
> versions.

IIUC only the test is faulty / unreliable, correct?

We have until Thursday before this patch hits Linus's tree so should 
be plenty of time to figure the problem out and apply an incremental
fix. I see you posted an RFC already, thanks!

> After that, a more proper discussion can be had about (1), and the
> regression tests can be fixed. I'm sending a demonstrative patch for
> that as a response to this message.