Subject: Re: [PATCH net] xfrm: Fix ignored return value in xfrm6_init()

From: Leon Romanovsky <[email-masked]>
Date: Sun, 6 Nov 2022 21:08:18 +0200

On Thu, Nov 03, 2022 at 05:07:13PM +0800, Chen Zhongjin wrote:
> When IPv6 module initializing in xfrm6_init(), register_pernet_subsys()
> is possible to fail but its return value is ignored.
> 
> If IPv6 initialization fails later and xfrm6_fini() is called,
> removing uninitialized list in xfrm6_net_ops will cause null-ptr-deref:
> 
> KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
> CPU: 1 PID: 330 Comm: insmod
> RIP: 0010:unregister_pernet_operations+0xc9/0x450
> Call Trace:
>  <TASK>
>  unregister_pernet_subsys+0x31/0x3e
>  xfrm6_fini+0x16/0x30 [ipv6]
>  ip6_route_init+0xcd/0x128 [ipv6]
>  inet6_init+0x29c/0x602 [ipv6]
>  ...
> 
> Fix it by catching the error return value of register_pernet_subsys().
> 
> Fixes: 8d068875caca ("xfrm: make gc_thresh configurable in all namespaces")
> Signed-off-by: Chen Zhongjin <[email-masked]>
> ---
>  net/ipv6/xfrm6_policy.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)

I see same error in net/ipv4/xfrm4_policy.c which introduced by same
commit mentioned in Fixes line.

Thanks

> 
> diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
> index 4a4b0e49ec92..ea435eba3053 100644
> --- a/net/ipv6/xfrm6_policy.c
> +++ b/net/ipv6/xfrm6_policy.c
> @@ -287,9 +287,13 @@ int __init xfrm6_init(void)
>  	if (ret)
>  		goto out_state;
>  
> -	register_pernet_subsys(&xfrm6_net_ops);
> +	ret = register_pernet_subsys(&xfrm6_net_ops);
> +	if (ret)
> +		goto out_protocol;
>  out:
>  	return ret;
> +out_protocol:
> +	xfrm6_protocol_fini();
>  out_state:
>  	xfrm6_state_fini();
>  out_policy:
> -- 
> 2.17.1
>