netdev - Re: [PATCH v6 bpf] xsk: fix immature cq descriptor production

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Message-ID: <089fa206-1511-4fd9-bc12-f73ab8a08bb6@iogearbox.net>
Date: Tue, 26 Aug 2025 14:23:34 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: Dan Carpenter <dan.carpenter@...aro.org>,
 Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Cc: bpf@...r.kernel.org, ast@...nel.org, andrii@...nel.org,
 netdev@...r.kernel.org, magnus.karlsson@...el.com, stfomichev@...il.com,
 aleksander.lobakin@...el.com, Eryk Kubanski <e.kubanski@...tner.samsung.com>
Subject: Re: [PATCH v6 bpf] xsk: fix immature cq descriptor production

On 8/26/25 10:14 AM, Dan Carpenter wrote:
> On Wed, Aug 20, 2025 at 05:44:16PM +0200, Maciej Fijalkowski wrote:
>>   			return ERR_PTR(err);
>>   
>>   		skb_reserve(skb, hr);
>> +
>> +		addrs = kmem_cache_zalloc(xsk_tx_generic_cache, GFP_KERNEL);
>> +		if (!addrs) {
>> +			kfree(skb);
> 
> This needs to be kfree_skb(skb);

Oh well, good catch! Maciej, given this commit did not land yet in Linus' tree,
I can toss the commit from bpf tree assuming you send a v7?

Also, looking at xsk_build_skb(), do we similarly need to free that allocated
skb when we hit the ERR_PTR(-EOVERFLOW) ? Mentioned function has the following
in the free_err path:

         if (first_frag && skb)
                 kfree_skb(skb);

Pls double check.

> regards,
> dan carpenter
> 
>> +			return ERR_PTR(-ENOMEM);
>> +		}
>> +
>> +		xsk_set_destructor_arg(skb, addrs);
>>   	}
>>   
>>   	addr = desc->addr;
>