linux-kernel - Re: [PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release

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Message-ID: <b3f2ac81-93e5-4143-a3fe-a5ff1159aaec@nbd.name>
Date: Mon, 12 Aug 2024 17:34:12 +0200
From: Felix Fietkau <nbd@....name>
To: Elad Yifee <eladwf@...il.com>
Cc: daniel@...rotopia.org, Sean Wang <sean.wang@...iatek.com>,
 Mark Lee <Mark-MC.Lee@...iatek.com>, Lorenzo Bianconi <lorenzo@...nel.org>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 Chen Lin <chen45464546@....com>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO
 rings release

On 12.08.24 17:21, Elad Yifee wrote:
> For LRO we allocate more than one page, yet 'skb_free_frag' is used
> to free the buffer, which only frees a single page.
> Fix it by using 'free_pages' instead.
> 
> Fixes: 2f2c0d2919a1 ("net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag")
> Signed-off-by: Elad Yifee <eladwf@...il.com>

Are you sure about this change? From what I can see, the LRO buffer is 
(or at least should be) allocated as a compound page. Because of that, 
skb_free_frag should work on it. If it doesn't, wouldn't we run into the 
same issue when the network stack frees received packets?

- Felix