netdev - Re: [PATCH ipsec] esp: limit skb_page_frag

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Message-ID: <20220413101557.GJ2517843@gauss3.secunet.de>
Date:   Wed, 13 Apr 2022 12:15:57 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Sabrina Dubroca <sd@...asysnail.net>
CC:     <netdev@...r.kernel.org>
Subject: Re: [PATCH ipsec] esp: limit skb_page_frag_refill use to a single
 page

On Wed, Apr 13, 2022 at 10:10:50AM +0200, Sabrina Dubroca wrote:
> Commit ebe48d368e97 ("esp: Fix possible buffer overflow in ESP
> transformation") tried to fix skb_page_frag_refill usage in ESP by
> capping allocsize to 32k, but that doesn't completely solve the issue,
> as skb_page_frag_refill may return a single page. If that happens, we
> will write out of bounds, despite the check introduced in the previous
> patch.
> 
> This patch forces COW in cases where we would end up calling
> skb_page_frag_refill with a size larger than a page (first in
> esp_output_head with tailen, then in esp_output_tail with
> skb->data_len).
> 
> Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
> Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible")
> Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>

Applied, thanks a lot Sabrina!