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Message-ID: <be794dca-f3ad-8fe4-98f2-2b17ea8ad72b@huawei.com>
Date: Tue, 1 Nov 2022 19:03:06 +0800
From: Chen Zhongjin <chenzhongjin@...wei.com>
To: <linux-kernel@...r.kernel.org>, <netfilter-devel@...r.kernel.org>,
<coreteam@...filter.org>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>
CC: <pablo@...filter.org>, <kadlec@...filter.org>, <fw@...len.de>,
<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
<pabeni@...hat.com>, <john.fastabend@...il.com>,
<lorenzo@...nel.org>, <ast@...nel.org>
Subject: Re: [PATCH] netfilter: nf_nat: Fix possible memory leak in
nf_nat_init()
On 2022/11/1 17:34, Chen Zhongjin wrote:
> In nf_nat_init(), register_nf_nat_bpf() can fail and return directly
> without any error handling.
> Then nf_nat_bysource will leak and registering of &nat_net_ops won't
> be reverted. This leaves wild ops in subsystem linkedlist and when
> another module tries to call register_pernet_operations() it triggers
> page fault:
>
> BUG: unable to handle page fault for address: fffffbfff81b964c
> RIP: 0010:register_pernet_operations+0x1b9/0x5f0
> Call Trace:
> <TASK>
> register_pernet_subsys+0x29/0x40
> ebtables_init+0x58/0x1000 [ebtables]
> ...
>
> Fixes: 820dc0523e05 ("net: netfilter: move bpf_ct_set_nat_info kfunc in nf_nat_bpf.c")
> Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
> ---
> net/netfilter/nf_nat_core.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
> index 18319a6e6806..b24b4dfc1ca4 100644
> --- a/net/netfilter/nf_nat_core.c
> +++ b/net/netfilter/nf_nat_core.c
> @@ -1152,7 +1152,12 @@ static int __init nf_nat_init(void)
> WARN_ON(nf_nat_hook != NULL);
> RCU_INIT_POINTER(nf_nat_hook, &nat_hook);
>
> - return register_nf_nat_bpf();
> + ret = register_nf_nat_bpf();
> + if (ret < 0) {
> + kvfree(nf_nat_bysource);
> + unregister_pernet_subsys(&nat_net_ops);
> + }
> + return ret;
> }
I noticed that follow_master_nat should also be unregistered.
Going to send v2, discard this one.
Best,
Chen
>
> static void __exit nf_nat_cleanup(void)
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