netdev - Re: [PATCH v2 net] sctp: avoid NULL dereference when chunk data buffer is missing

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Message-ID: <aPeNu7-COwBQS21U@t14s.localdomain>
Date: Tue, 21 Oct 2025 10:42:19 -0300
From: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To: Alexey Simakov <bigalex934@...il.com>
Cc: Xin Long <lucien.xin@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>, linux-sctp@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: Re: [PATCH v2 net] sctp: avoid NULL dereference when chunk data
 buffer is missing

On Tue, Oct 21, 2025 at 04:00:36PM +0300, Alexey Simakov wrote:
> chunk->skb pointer is dereferenced in the if-block where it's supposed
> to be NULL only.
> 
> chunk->skb can only be NULL if chunk->head_skb is not. Check for frag_list
> instead and do it just before replacing chunk->skb. We're sure that
> otherwise chunk->skb is non-NULL because of outer if() condition.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 90017accff61 ("sctp: Add GSO support")
> Signed-off-by: Alexey Simakov <bigalex934@...il.com>

Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>

Thx.