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From: David Ahern <dsahern@gmail.com>
To: Andrew Kanner <andrew.kanner@gmail.com>,
	davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
	pabeni@redhat.com, jasowang@redhat.com, netdev@vger.kernel.org,
	brouer@redhat.com, jbrouer@redhat.com, john.fastabend@gmail.com,
	linux-kernel@vger.kernel.org
Cc: syzbot+f817490f5bd20541b90a@syzkaller.appspotmail.com,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [PATCH v4 1/2] drivers: net: prevent tun_build_skb() to exceed the packet size limit
Date: Tue, 1 Aug 2023 19:07:39 -0600	[thread overview]
Message-ID: <3fa4d25d-7fea-d25b-fa83-4ada2c550725@gmail.com> (raw)
In-Reply-To: <20230801220710.464-1-andrew.kanner@gmail.com>

On 8/1/23 4:07 PM, Andrew Kanner wrote:
> @@ -1594,7 +1597,13 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile,
>  	if (zerocopy)
>  		return false;
>  
> -	if (SKB_DATA_ALIGN(len + TUN_RX_PAD) +
> +	rcu_read_lock();
> +	xdp_prog = rcu_dereference(tun->xdp_prog);
> +	if (xdp_prog)
> +		pad += XDP_PACKET_HEADROOM;
> +	rcu_read_unlock();


since you do not care about the actual xdp_prog (only that one is set) I
believe you can use rcu_access_pointer here.
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WARNING: multiple messages have this Message-ID (diff)
From: David Ahern <dsahern@gmail.com>
To: Andrew Kanner <andrew.kanner@gmail.com>,
	davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
	pabeni@redhat.com, jasowang@redhat.com, netdev@vger.kernel.org,
	brouer@redhat.com, jbrouer@redhat.com, john.fastabend@gmail.com,
	linux-kernel@vger.kernel.org
Cc: linux-kernel-mentees@lists.linuxfoundation.org,
	syzbot+f817490f5bd20541b90a@syzkaller.appspotmail.com
Subject: Re: [PATCH v4 1/2] drivers: net: prevent tun_build_skb() to exceed the packet size limit
Date: Tue, 1 Aug 2023 19:07:39 -0600	[thread overview]
Message-ID: <3fa4d25d-7fea-d25b-fa83-4ada2c550725@gmail.com> (raw)
In-Reply-To: <20230801220710.464-1-andrew.kanner@gmail.com>

On 8/1/23 4:07 PM, Andrew Kanner wrote:
> @@ -1594,7 +1597,13 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile,
>  	if (zerocopy)
>  		return false;
>  
> -	if (SKB_DATA_ALIGN(len + TUN_RX_PAD) +
> +	rcu_read_lock();
> +	xdp_prog = rcu_dereference(tun->xdp_prog);
> +	if (xdp_prog)
> +		pad += XDP_PACKET_HEADROOM;
> +	rcu_read_unlock();


since you do not care about the actual xdp_prog (only that one is set) I
believe you can use rcu_access_pointer here.

  parent reply	other threads:[~2023-08-02  1:07 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-01 22:07 [PATCH v4 1/2] drivers: net: prevent tun_build_skb() to exceed the packet size limit Andrew Kanner
2023-08-01 22:07 ` Andrew Kanner
2023-08-01 22:07 ` [PATCH v4 2/2] net: core: remove unnecessary frame_sz check in bpf_xdp_adjust_tail() Andrew Kanner
2023-08-01 22:07   ` Andrew Kanner
2023-08-02 13:56   ` Jesper Dangaard Brouer
2023-08-02 13:56     ` Jesper Dangaard Brouer
2023-08-03  3:20   ` Jason Wang
2023-08-03  3:20     ` Jason Wang
2023-08-03 18:06     ` Andrew Kanner
2023-08-03 18:06       ` Andrew Kanner
2023-08-02  1:07 ` David Ahern [this message]
2023-08-02  1:07   ` [PATCH v4 1/2] drivers: net: prevent tun_build_skb() to exceed the packet size limit David Ahern
2023-08-02 12:16   ` Andrew Kanner
2023-08-02 12:16     ` Andrew Kanner
2023-08-02 14:13 ` Jesper Dangaard Brouer
2023-08-02 14:13   ` Jesper Dangaard Brouer
2023-08-03  3:19   ` Jason Wang
2023-08-03  3:19     ` Jason Wang
2023-08-03 17:53     ` Andrew Kanner
2023-08-03 17:53       ` Andrew Kanner
2023-08-04  9:30       ` Jesper Dangaard Brouer
2023-08-04  9:30         ` Jesper Dangaard Brouer

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