Re: [PATCH v1 net] tcp: Don't call skb_clone_and_charge_r() for close()d listener in tcp_v6_do_rcv().

[Xuanqiang Luo <xuanqiang.luo@linux.dev>]

在 2026/9/14 09:14, Kuniyuki Iwashima 写道:
> tcp_v6_do_rcv() no longer calls skb_clone_and_charge_r() for
> TCP_LISTEN since commit 073d89808c06 ("net: fix data-races around
> sk->sk_forward_alloc").
> 
> However, there is still a small race window between tcp_v6_rcv()
> and tcp_v6_do_rcv(), where concurrent close() changes TCP_LISTEN
> to TCP_CLOSE, causing skb_clone_and_charge_r() to be called
> locklessly and resulting in the splat below. [0]
> 
> Let's avoid calling skb_clone_and_charge_r() for TCP_CLOSE as well.
> 
> This is fine for non-listeners because tcp_rcv_state_process()
> drops skb for TCP_CLOSE and opt_skb was freed immediately anyway.
> 
> [0]:
> sk->sk_forward_alloc
> WARNING: net/ipv4/af_inet.c:162 at inet_sock_destruct+0x64d/0x810 net/ipv4/af_inet.c:162, CPU#1: ksoftirqd/1/28
> Modules linked in:
> CPU: 1 UID: 0 PID: 28 Comm: ksoftirqd/1 Not tainted 7.2.0 #17 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
> RIP: 0010:inet_sock_destruct+0x64d/0x810 net/ipv4/af_inet.c:162
> Code: 3d 49 ff e9 06 fd ff ff e8 d0 5b 83 f8 90 0f 0b 90 e9 35 fe ff ff e8 c2 5b 83 f8 90 0f 0b 90 e9 c5 fe ff ff e8 b4 5b 83 f8 90 <0f> 0b 90 e9 04 ff ff ff e8 a6 5b 83 f8 90 0f 0b 90 e9 65 fe ff ff
> RSP: 0018:ffffc90000677bb8 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff8880117bde80 RCX: ffffffff8957eb41
> RDX: ffff88801dad5d00 RSI: ffffffff8957ec3c RDI: 0000000000000005
> RBP: 00000000fffff000 R08: ffffffff8957eb41 R09: 00000000fffff000
> R10: 0000000000000005 R11: 0000000000000000 R12: dffffc0000000000
> R13: ffff8880117bdf10 R14: ffffffff81c08eb7 R15: 0000000000000003
> FS:  0000000000000000(0000) GS:ffff8880d7ae5000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f93a1021138 CR3: 00000000207a9000 CR4: 0000000000350ef0
> Call Trace:
>   <TASK>
>   __sk_destruct+0x82/0xae0 net/core/sock.c:2356
>   rcu_do_batch kernel/rcu/tree.c:2645 [inline]
>   rcu_core+0x59c/0x1100 kernel/rcu/tree.c:2897
>   handle_softirqs+0x1e4/0x9b0 kernel/softirq.c:622
>   run_ksoftirqd kernel/softirq.c:1076 [inline]
>   run_ksoftirqd+0x38/0x60 kernel/softirq.c:1068
>   smpboot_thread_fn+0x458/0xc80 kernel/smpboot.c:160
>   kthread+0x396/0x4a0 kernel/kthread.c:436
>   ret_from_fork+0x8e0/0xe40 arch/x86/kernel/process.c:158
>   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>   </TASK>
> 
> Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
> Reported-by: Taras Madan <tarasmadan@google.com>
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>

Reviewed-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

Thanks,