From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>,
Qingfang Deng <qingfang.deng@linux.dev>,
Breno Leitao <leitao@debian.org>,
Norbert Szetei <norbert@doyensec.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Taegu Ha <hataegu0826@gmail.com>, Kees Cook <kees@kernel.org>,
linux-ppp@vger.kernel.org, linux-kernel@vger.kernel.org,
Guillaume Nault <gnault@redhat.com>,
netdev@vger.kernel.org, Luis Chamberlain <mcgrof@kernel.org>,
Daniel Gomez <da.gomez@kernel.org>,
Sami Tolvanen <samitolvanen@google.com>,
Aaron Tomlin <atomlin@atomlin.com>,
linux-modules@vger.kernel.org
Subject: Re: [PATCH net v2] ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF
Date: Wed, 8 Jul 2026 11:11:47 +0200 [thread overview]
Message-ID: <20260708091147.O1d41Vi0@linutronix.de> (raw)
In-Reply-To: <7ff3af97-1c10-4f46-84ae-ffbf757f7e9e@paulmck-laptop>
On 2026-07-07 09:39:01 [-0700], Paul E. McKenney wrote:
> Alternatives include:
>
> o Provide a patch like that above, but only execute the
> rcu_barrier() in some debug mode. If your code works when
> that debug is enabled but does not otherwise, you add the
> rcu_barrier().
>
> o If debug is enabled, make rcu_do_batch() check the function
> before invoking it. If the function is not mapped, issue a
> diagnostic, and don't try to invoke the function. (But is
> there a sufficiently cheap way to check for the function not
> being mapped?)
In both cases you would see a backtrace and the name of the last
unloaded module. And since we don't see a lot of these reports, people
either don't run into this because it does not exist or RCU is quick
enough.
>
> Thanx, Paul
Sebastian
next prev parent reply other threads:[~2026-07-08 9:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <D9C0245B-608B-4884-8A09-F55BA4A9F948@doyensec.com>
[not found] ` <de2616b3-6edf-4255-ba77-0674e225ab27@linux.dev>
[not found] ` <akfjpBVML_1RFF91@gmail.com>
[not found] ` <87111f02-5b7a-4185-8364-2faba650578b@linux.dev>
2026-07-06 9:29 ` [PATCH net v2] ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF Sebastian Andrzej Siewior
2026-07-07 15:32 ` Petr Pavlu
2026-07-07 16:39 ` Paul E. McKenney
2026-07-08 9:11 ` Sebastian Andrzej Siewior [this message]
2026-07-08 14:01 ` Paul E. McKenney
2026-07-08 7:49 ` Sebastian Andrzej Siewior
2026-07-08 13:04 ` Petr Pavlu
2026-07-08 13:56 ` Sebastian Andrzej Siewior
2026-07-08 19:00 ` Sebastian Andrzej Siewior
2026-07-08 19:22 ` Paul E. McKenney
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