linux-kernel - Re: [PATCH] llc: fix uninit-value in __llc_lookup

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Message-ID: <20231206062712.41467-1-kuniyu@amazon.com>
Date:   Wed, 6 Dec 2023 15:27:12 +0900
From:   Kuniyuki Iwashima <kuniyu@...zon.com>
To:     <eadavis@...com>
CC:     <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <pabeni@...hat.com>,
        <syzbot+b5ad66046b913bc04c6f@...kaller.appspotmail.com>,
        <syzkaller-bugs@...glegroups.com>, <kuniyu@...zon.com>
Subject: Re: [PATCH] llc: fix uninit-value in __llc_lookup_established

From: Edward Adam Davis <eadavis@...com>
Date: Wed,  6 Dec 2023 09:55:15 +0800
> llc only supports ETH_P_802_2 protocol, so drop the skb when the protocol is 
> not it.

This is not true.  ETH_P_TR_802_2 is also processed by llc_rcv().

Let me post this formally.
https://lore.kernel.org/netdev/20231206005340.11534-1-kuniyu@amazon.com/

> 
> Reported-by: syzbot+b5ad66046b913bc04c6f@...kaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@...com>
> ---
>  net/llc/llc_input.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/llc/llc_input.c b/net/llc/llc_input.c
> index 51bccfb00a9c..16b2c57f38c2 100644
> --- a/net/llc/llc_input.c
> +++ b/net/llc/llc_input.c
> @@ -141,7 +141,8 @@ static inline int llc_fixup_skb(struct sk_buff *skb)
>  			return 0;
>  		if (unlikely(pskb_trim_rcsum(skb, data_size)))
>  			return 0;
> -	}
> +	} else
> +		return 0;
>  	return 1;
>  }
>  
> -- 
> 2.43.0