netdev - Re: [PATCH net] bonding: provide a net pointer to __skb_flow

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Message-ID: <aW_fEILfgvum4B1c@mini-arch>
Date: Tue, 20 Jan 2026 12:01:20 -0800
From: Stanislav Fomichev <stfomichev@...il.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>, netdev@...r.kernel.org,
	eric.dumazet@...il.com,
	syzbot+c46409299c70a221415e@...kaller.appspotmail.com,
	Matteo Croce <mcroce@...hat.com>,
	Stanislav Fomichev <sdf@...ichev.me>
Subject: Re: [PATCH net] bonding: provide a net pointer to
 __skb_flow_dissect()

On 01/20, Eric Dumazet wrote:
> After 3cbf4ffba5ee ("net: plumb network namespace into __skb_flow_dissect")
> we have to provide a net pointer to __skb_flow_dissect(),
> either via skb->dev, skb->sk, or a user provided pointer.
> 
> In the following case, syzbot was able to cook a bare skb.
> 
> WARNING: net/core/flow_dissector.c:1131 at __skb_flow_dissect+0xb57/0x68b0 net/core/flow_dissector.c:1131, CPU#1: syz.2.1418/11053
> Call Trace:
>  <TASK>
>   bond_flow_dissect drivers/net/bonding/bond_main.c:4093 [inline]
>   __bond_xmit_hash+0x2d7/0xba0 drivers/net/bonding/bond_main.c:4157
>   bond_xmit_hash_xdp drivers/net/bonding/bond_main.c:4208 [inline]
>   bond_xdp_xmit_3ad_xor_slave_get drivers/net/bonding/bond_main.c:5139 [inline]
>   bond_xdp_get_xmit_slave+0x1fd/0x710 drivers/net/bonding/bond_main.c:5515
>   xdp_master_redirect+0x13f/0x2c0 net/core/filter.c:4388
>   bpf_prog_run_xdp include/net/xdp.h:700 [inline]
>   bpf_test_run+0x6b2/0x7d0 net/bpf/test_run.c:421
>   bpf_prog_test_run_xdp+0x795/0x10e0 net/bpf/test_run.c:1390
>   bpf_prog_test_run+0x2c7/0x340 kernel/bpf/syscall.c:4703
>   __sys_bpf+0x562/0x860 kernel/bpf/syscall.c:6182
>   __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
>   __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
>   __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6272
>   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>   do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
> 
> Fixes: 58deb77cc52d ("bonding: balance ICMP echoes in layer3+4 mode")
> Reported-by: syzbot+c46409299c70a221415e@...kaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/696faa23.050a0220.4cb9c.001f.GAE@google.com/T/#u
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Matteo Croce <mcroce@...hat.com>
> Cc: Stanislav Fomichev <sdf@...ichev.me>

Acked-by: Stanislav Fomichev <sdf@...ichev.me>