From: Florian Westphal <fw@strlen•de>
To: Eric Dumazet <edumazet@google•com>
Cc: Jiawei Ye <jiawei.ye@foxmail•com>,
pablo@netfilter•org, kadlec@netfilter•org, davem@davemloft•net,
dsahern@kernel•org, kuba@kernel•org, pabeni@redhat•com,
fw@strlen•de, netfilter-devel@vger•kernel.org,
coreteam@netfilter•org, netdev@vger•kernel.org,
linux-kernel@vger•kernel.org
Subject: Re: [PATCH] netfilter: tproxy: Add RCU protection in nf_tproxy_laddr4
Date: Wed, 4 Sep 2024 14:48:40 +0200 [thread overview]
Message-ID: <20240904124840.GA15053@breakpoint.cc> (raw)
In-Reply-To: <CANn89iLQuBYht_jMx7WwtbDP-PTnhBvNu2FWW1uGnKkcqnvT+w@mail.gmail.com>
Eric Dumazet <edumazet@google•com> wrote:
> On Wed, Sep 4, 2024 at 2:25 PM Jiawei Ye <jiawei.ye@foxmail•com> wrote:
> >
> > In the `nf_tproxy_laddr4` function, both the `__in_dev_get_rcu()` call
> > and the `in_dev_for_each_ifa_rcu()` macro are used to access
> > RCU-protected data structures. Previously, these accesses were not
> > enclosed within an RCU read-side critical section, which violates RCU
> > usage rules and can lead to race conditions, data inconsistencies, and
> > memory corruption issues.
> >
> > This possible bug was identified using a static analysis tool developed
> > by myself, specifically designed to detect RCU-related issues.
> >
> > To address this, `rcu_read_lock()` and `rcu_read_unlock()` are added
> > around the RCU-protected operations in the `nf_tproxy_laddr4` function by
> > acquiring the RCU read lock before calling `__in_dev_get_rcu()` and
> > iterating with `in_dev_for_each_ifa_rcu()`. This change prevents
> > potential RCU issues and adheres to proper RCU usage patterns.
>
> Please share with us the complete stack trace where you think rcu is not held,
> because your static tool is unknown to us.
>
> nf_tproxy_get_sock_v4() would have a similar issue.
Right, all netfilter hooks assume rcu read lock is held.
See nf_hook()/nf_hook_slow().
next prev parent reply other threads:[~2024-09-04 12:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-04 12:18 [PATCH] netfilter: tproxy: Add RCU protection in nf_tproxy_laddr4 Jiawei Ye
2024-09-04 12:32 ` Eric Dumazet
2024-09-04 12:48 ` Florian Westphal [this message]
2024-09-05 11:53 ` kernel test robot
2024-09-05 15:41 ` kernel test robot
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