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Message-ID: <Z8iUG8aTF9Kww09z@pop-os.localdomain>
Date: Wed, 5 Mar 2025 10:12:43 -0800
From: Cong Wang <xiyou.wangcong@...il.com>
To: Dong Chenchen <dongchenchen2@...wei.com>
Cc: edumazet@...gle.com, kuniyu@...zon.com, pabeni@...hat.com,
willemb@...gle.com, john.fastabend@...il.com, jakub@...udflare.com,
davem@...emloft.net, kuba@...nel.org, horms@...nel.org,
daniel@...earbox.net, netdev@...r.kernel.org, bpf@...r.kernel.org,
zhangchangzhong@...wei.com, weiyongjun1@...wei.com
Subject: Re: [PATCH net] bpf, sockmap: Restore sk_prot ops when psock is
removed from sockmap
On Wed, Mar 05, 2025 at 10:02:34PM +0800, Dong Chenchen wrote:
> WARNING: CPU: 0 PID: 6558 at net/core/sock_map.c:1703 sock_map_close+0x3c4/0x480
> Modules linked in:
> CPU: 0 UID: 0 PID: 6558 Comm: syz-executor.14 Not tainted 6.14.0-rc5+ #238
> RIP: 0010:sock_map_close+0x3c4/0x480
> Call Trace:
> <TASK>
> inet_release+0x144/0x280
> __sock_release+0xb8/0x270
> sock_close+0x1e/0x30
> __fput+0x3c6/0xb30
> __fput_sync+0x7b/0x90
> __x64_sys_close+0x90/0x120
> do_syscall_64+0x5d/0x170
> entry_SYSCALL_64_after_hwframe+0x76/0x7e
>
> The root cause is:
> sock_hash_update_common
> sock_map_unref
> sock_map_del_link
> psock->psock_update_sk_prot(sk, psock, false);
> //false won't restore proto
> sk_psock_put
> rcu_assign_sk_user_data(sk, NULL);
> inet_release
> sk->sk_prot->close
> sock_map_close
> WARN(sk->sk_prot->close == sock_map_close)
>
> When psock is removed from sockmap, sock_map_del_link() still set
> sk->sk_prot to bpf proto instead of restore it (for incorrect restore
> value). sock release will triger warning of sock_map_close() for
> recurse after psock drop.
But sk_psock_drop() restores it with sk_psock_restore_proto() after the
psock reference count goes to zero. So how could the above happen?
By the way, it would be perfect if you could add a test case for it
together with this patch (a followup patch is fine too).
Thanks!
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