netdev - [PATCH net] bpf, sockmap: Restore sk_prot ops when psock is removed from sockmap

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Message-ID: <20250305140234.2082644-1-dongchenchen2@huawei.com>
Date: Wed, 5 Mar 2025 22:02:34 +0800
From: Dong Chenchen <dongchenchen2@...wei.com>
To: <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>
CC: <netdev@...r.kernel.org>, <bpf@...r.kernel.org>,
	<zhangchangzhong@...wei.com>, <weiyongjun1@...wei.com>, Dong Chenchen
	<dongchenchen2@...wei.com>
Subject: [PATCH net] bpf, sockmap: Restore sk_prot ops when psock is removed from sockmap

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.

Set restore param of psock_update_sk_prot to true to fix the problem.

Fixes: c0d95d3380ee ("bpf, sockmap: Re-evaluate proto ops when psock is removed from sockmap")
Signed-off-by: Dong Chenchen <dongchenchen2@...wei.com>
---
 net/core/sock_map.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 82a14f131d00..10bc185ef103 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -171,7 +171,7 @@ static void sock_map_del_link(struct sock *sk,
 			sk_psock_stop_verdict(sk, psock);
 
 		if (psock->psock_update_sk_prot)
-			psock->psock_update_sk_prot(sk, psock, false);
+			psock->psock_update_sk_prot(sk, psock, true);
 		write_unlock_bh(&sk->sk_callback_lock);
 	}
 }
-- 
2.25.1