linux-kernel - Re: [PATCH v3] wifi: cfg80211: Fix uninitialized header access in cfg80211

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Message-ID: <fb7ef6bcbfed2e98cd8266325e681f30873a3784.camel@sipsolutions.net>
Date: Wed, 19 Nov 2025 10:09:13 +0100
From: Johannes Berg <johannes@...solutions.net>
To: Ranganath V N <vnranganath.20@...il.com>, dave.taht@...ferbloat.net, 
	linville@...driver.com
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org, 
	skhan@...uxfoundation.org, david.hunter.linux@...il.com, khalid@...nel.org,
 	syzbot+878ddc3962f792e9af59@...kaller.appspotmail.com
Subject: Re: [PATCH v3] wifi: cfg80211: Fix uninitialized header access in
 cfg80211_classify8021d

On Tue, 2025-11-18 at 20:35 +0530, Ranganath V N wrote:
> 
>  	switch (skb->protocol) {
>  	case htons(ETH_P_IP):
> +		struct iphdr iph, *ip;
> +
> +		ip = skb_header_pointer(skb, sizeof(struct ethhdr),
> +					sizeof(*ip), &iph);
> +		if (!ip)
> +			return 0;
> +
>  		dscp = ipv4_get_dsfield(ip_hdr(skb)) & 0xfc;

If you pull it out that way, seems you should also _use_ it?

johannes