netdev - Re: [PATCH] net/smc: Fix possible leaked pernet namespace in smc

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Message-ID: <f51d6df1-4d85-8b65-2480-e626037287aa@linux.ibm.com>
Date:   Tue, 1 Nov 2022 13:54:12 +0100
From:   Wenjia Zhang <wenjia@...ux.ibm.com>
To:     Chen Zhongjin <chenzhongjin@...wei.com>,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        netdev@...r.kernel.org
Cc:     kgraul@...ux.ibm.com, jaka@...ux.ibm.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        guvenc@...ux.ibm.com
Subject: Re: [PATCH] net/smc: Fix possible leaked pernet namespace in
 smc_init()



On 01.11.22 10:37, Chen Zhongjin wrote:
> In smc_init(), register_pernet_subsys(&smc_net_stat_ops) is called
> without any error handling.
> If it fails, registering of &smc_net_ops won't be reverted.
> And if smc_nl_init() fails, &smc_net_stat_ops itself 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: 194730a9beb5 ("net/smc: Make SMC statistics network namespace aware")
> Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>

It looks good, thank you for the effort!

Reviewed-by: Wenjia Zhang <wenjia@...ux.ibm.com>
> ---
>   net/smc/af_smc.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> index 3ccbf3c201cd..e12d4fa5aece 100644
> --- a/net/smc/af_smc.c
> +++ b/net/smc/af_smc.c
> @@ -3380,14 +3380,14 @@ static int __init smc_init(void)
>   
>   	rc = register_pernet_subsys(&smc_net_stat_ops);
>   	if (rc)
> -		return rc;
> +		goto out_pernet_subsys;
>   
>   	smc_ism_init();
>   	smc_clc_init();
>   
>   	rc = smc_nl_init();
>   	if (rc)
> -		goto out_pernet_subsys;
> +		goto out_pernet_subsys_stat;
>   
>   	rc = smc_pnet_init();
>   	if (rc)
> @@ -3480,6 +3480,8 @@ static int __init smc_init(void)
>   	smc_pnet_exit();
>   out_nl:
>   	smc_nl_exit();
> +out_pernet_subsys_stat:
> +	unregister_pernet_subsys(&smc_net_stat_ops);
>   out_pernet_subsys:
>   	unregister_pernet_subsys(&smc_net_ops);
>