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From: Florian Westphal <fw@strlen.de>
To: "Igor A. Artemiev" <Igor.A.Artemiev@mcst.ru>
Cc: Florian Westphal <fw@strlen.de>,
	Pablo Neira Ayuso <pablo@netfilter.org>,
	Jozsef Kadlecsik <kadlec@netfilter.org>,
	"David S . Miller" <davem@davemloft.net>,
	Paolo Abeni <pabeni@redhat.com>, Jakub Kicinski <kuba@kernel.org>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	lvc-project@linuxtesting.org
Subject: Re: [lvc-project] [PATCH] netfilter: ebtables: remove unnecessary NULL check
Date: Wed, 21 Jun 2023 12:46:03 +0200	[thread overview]
Message-ID: <20230621104603.GA24035@breakpoint.cc> (raw)
In-Reply-To: <f687fe6f-3330-a9c5-4760-f753638c7b03@mcst.ru>

Igor A. Artemiev <Igor.A.Artemiev@mcst.ru> wrote:
> On 6/20/23 19:38, Florian Westphal wrote:
> > Igor Artemiev <Igor.A.Artemiev@mcst.ru> wrote:
> > > In ebt_do_table() 'private->chainstack' cannot be NULL
> > > and the 'cs' pointer is dereferenced below, so it does not make
> > > sense to compare 'private->chainstack' with NULL.
> > ?  Why do you think that?
> > 
> The 'cs' pointer is dereferenced below without checking, as it is assumed to
> always be initialized with 'private->chainstack[smp_processor_id()]'.

No, its not.  The dereferencing is conditional, as is the allocation
of the chainstack.

No user defined chains, no chain stack.

With this change, "ebtables-legacy -A INPUT" causes kernel panic.

      reply	other threads:[~2023-06-21 10:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-20 15:25 [lvc-project] [PATCH] netfilter: ebtables: remove unnecessary NULL check Igor Artemiev
2023-06-20 16:38 ` Florian Westphal
2023-06-21 10:49   ` Igor A. Artemiev
2023-06-21 10:46     ` Florian Westphal [this message]

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