netdev - Re: [net/netlink] Question about potential memleak in netlink_proto

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Date: Fri, 15 Mar 2024 01:53:47 +0100
From: Florian Westphal <fw@...len.de>
To: Chenyuan Yang <chenyuan0y@...il.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, horms@...nel.org, anjali.k.kulkarni@...cle.com,
	pctammela@...atatu.com, andriy.shevchenko@...ux.intel.com,
	dhowells@...hat.com, kuniyu@...zon.com, netdev@...r.kernel.org,
	zzjas98@...il.com
Subject: Re: [net/netlink] Question about potential memleak in
 netlink_proto_init()

Chenyuan Yang <chenyuan0y@...il.com> wrote:
> Dear Netlink Developers,
> 
> We are curious whether the function `netlink_proto_init()` might have a memory leak.

Yes, but

> The function is https://elixir.bootlin.com/linux/v6.8/source/net/netlink/af_netlink.c#L2908
> and the relevant code is
> ```
> static int __init netlink_proto_init(void)
> {
> 	int i;
>   ...
> 
> 	for (i = 0; i < MAX_LINKS; i++) {
> 		if (rhashtable_init(&nl_table[i].hash,
> 				    &netlink_rhashtable_params) < 0) {
> 			while (--i > 0)
> 				rhashtable_destroy(&nl_table[i].hash);
> 			kfree(nl_table);
> 			goto panic;

... this calls panic(), kernel will crash intentionally.

Perhaps best patch would be to remove this error handling
and panic straight away, this is pretty much dead code.