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Date: Mon, 24 Aug 2026 17:16:38 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: Li Xiasong <lixiasong1@huawei.com>
Cc: stable@vger.kernel.org, Eric Dumazet <edumazet@google.com>,
	David Ahern <dsahern@kernel.org>, Ido Schimmel <idosch@nvidia.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Simon Horman <horms@kernel.org>, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, yuehaibing@huawei.com,
	zhangchangzhong@huawei.com, weiyongjun1@huawei.com
Subject: Re: [PATCH linux-6.1.y linux-6.6.y linux-6.12.y 0/1] ndisc: backport
 ndisc_send_redirect() cleanup
Message-ID: <2026082425-struck-compacter-2bdf@gregkh>
References: <20260824133852.328978-1-lixiasong1@huawei.com>
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In-Reply-To: <20260824133852.328978-1-lixiasong1@huawei.com>

On Mon, Aug 24, 2026 at 09:38:51PM +0800, Li Xiasong wrote:
> Please consider backporting upstream 0784d83df3bf to 6.1.y,
> 6.6.y and 6.12.y. It looks like the missing prerequisite for
> dbc3791e3b24 ("net: do not send ICMP/NDISC Redirects when peer
> allocation fails") already queued on these trees.
> 
> dbc3791e3b24 adds "if (!peer) goto release;" inside
> rcu_read_lock()/rcu_read_unlock() in ndisc_send_redirect(),
> which seems to leak the read lock on the NULL-peer path on
> these trees. This cleanup drops the pair (callers already hold
> rcu_read_lock()), so the leak would go away.
> 
> The patch below is against 6.12.y; the identical change applies
> to 6.1.y and 6.6.y.

Thanks for noticing this and the backport.