From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D9222334C0D for ; Thu, 28 May 2026 07:53:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779954829; cv=none; b=Sf+YlKH+2iGNKWAryq7Ig96/xGp27qzgEvgN/ORMMnppc7RdgY+T340p8s8yR7kuOkFrtSPgSYuLHFGSz0Ek1oFZCm8JCBNmJwN0lbbo66nUu/GqhUys31j5cIKNDnZJZKI46eSYCid93YMCAw4o5yu4StwdnLtJ23+WsM9+P7k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779954829; c=relaxed/simple; bh=geV0vRtyqHTJZuVWLhKSm5Ck26ViLeudWdzc7pJT+Tk=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=ZYggUuzNRKX5rbCOw4dUkF3awV1wsmVBlxPS+lfYMzV2dda/JJDlEbwO0exiReqJVgox5+GEAXCyLuUwuH+LzewuXTu5hIR8/C/csdcQuiS3K4fp5pmA19VhBxrwWV2elmXP+tN3v+lFZxVJbFiy4WoeRaxzuxrLYT6DcEsdx3Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BBsKW2Vq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="BBsKW2Vq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D9AF81F000E9; Thu, 28 May 2026 07:53:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779954827; bh=OcV9JZ7fXpBUwj4+SrtbTO6sMOG9ypJz6WRGwlwJFx4=; h=Subject:To:Cc:From:Date; b=BBsKW2VqCX0fTPNrRhoLtY3eFNYMvpGan2SHnr5bzUCOlkStq27ti9ZUOKFj7zWNS 9Ze6UIi60JaCCTiuFlQXgKd4oiJfMF8J0b21zkoUcV8n71pm7fPPaasRjb7OoovQTK HpxNEXo9wL7qEW/EToaykpw/jm3q+PvkaJX3zOOg= Subject: FAILED: patch "[PATCH] Bluetooth: serialize accept_q access" failed to apply to 5.10-stable tree To: wangjiexun2025@gmail.com,bird@lzu.edu.cn,jannh@google.com,luiz.von.dentz@intel.com,n05ec@lzu.edu.cn,tomapufckgml@gmail.com,yifanwucs@gmail.com,yuantan098@gmail.com Cc: From: Date: Thu, 28 May 2026 09:52:43 +0200 Message-ID: <2026052843-prankish-sharpener-ccb5@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x e83f5e24da741fa9405aeeff00b08c5ee7c37b88 # git commit -s git send-email --to '' --in-reply-to '2026052843-prankish-sharpener-ccb5@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From e83f5e24da741fa9405aeeff00b08c5ee7c37b88 Mon Sep 17 00:00:00 2001 From: Jiexun Wang Date: Wed, 6 May 2026 19:43:30 +0800 Subject: [PATCH] Bluetooth: serialize accept_q access bt_sock_poll() walks the accept queue without synchronization, while child teardown can unlink the same socket and drop its last reference. The unsynchronized accept queue walk has existed since the initial Bluetooth import. Protect accept_q with a dedicated lock for queue updates and polling. Also rework bt_accept_dequeue() to take temporary child references under the queue lock before dropping it and locking the child socket. Fixes: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reported-by: Jann Horn Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Jiexun Wang Signed-off-by: Ren Wei Signed-off-by: Jiexun Wang Reviewed-by: Jann Horn Signed-off-by: Luiz Augusto von Dentz diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h index 69eed69f7f26..3faea66b1979 100644 --- a/include/net/bluetooth/bluetooth.h +++ b/include/net/bluetooth/bluetooth.h @@ -398,6 +398,7 @@ void baswap(bdaddr_t *dst, const bdaddr_t *src); struct bt_sock { struct sock sk; struct list_head accept_q; + spinlock_t accept_q_lock; /* protects accept_q */ struct sock *parent; unsigned long flags; void (*skb_msg_name)(struct sk_buff *, void *, int *); diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c index 33d053d63407..9d68dd86023c 100644 --- a/net/bluetooth/af_bluetooth.c +++ b/net/bluetooth/af_bluetooth.c @@ -154,6 +154,7 @@ struct sock *bt_sock_alloc(struct net *net, struct socket *sock, sock_init_data(sock, sk); INIT_LIST_HEAD(&bt_sk(sk)->accept_q); + spin_lock_init(&bt_sk(sk)->accept_q_lock); sock_reset_flag(sk, SOCK_ZAPPED); @@ -214,6 +215,7 @@ void bt_accept_enqueue(struct sock *parent, struct sock *sk, bool bh) { const struct cred *old_cred; struct pid *old_pid; + struct bt_sock *par = bt_sk(parent); BT_DBG("parent %p, sk %p", parent, sk); @@ -224,9 +226,13 @@ void bt_accept_enqueue(struct sock *parent, struct sock *sk, bool bh) else lock_sock_nested(sk, SINGLE_DEPTH_NESTING); - list_add_tail(&bt_sk(sk)->accept_q, &bt_sk(parent)->accept_q); bt_sk(sk)->parent = parent; + spin_lock_bh(&par->accept_q_lock); + list_add_tail(&bt_sk(sk)->accept_q, &par->accept_q); + sk_acceptq_added(parent); + spin_unlock_bh(&par->accept_q_lock); + /* Copy credentials from parent since for incoming connections the * socket is allocated by the kernel. */ @@ -244,8 +250,6 @@ void bt_accept_enqueue(struct sock *parent, struct sock *sk, bool bh) bh_unlock_sock(sk); else release_sock(sk); - - sk_acceptq_added(parent); } EXPORT_SYMBOL(bt_accept_enqueue); @@ -254,45 +258,72 @@ EXPORT_SYMBOL(bt_accept_enqueue); */ void bt_accept_unlink(struct sock *sk) { + struct sock *parent = bt_sk(sk)->parent; + BT_DBG("sk %p state %d", sk, sk->sk_state); + spin_lock_bh(&bt_sk(parent)->accept_q_lock); list_del_init(&bt_sk(sk)->accept_q); - sk_acceptq_removed(bt_sk(sk)->parent); + sk_acceptq_removed(parent); + spin_unlock_bh(&bt_sk(parent)->accept_q_lock); bt_sk(sk)->parent = NULL; sock_put(sk); } EXPORT_SYMBOL(bt_accept_unlink); +static struct sock *bt_accept_get(struct sock *parent, struct sock *sk) +{ + struct bt_sock *bt = bt_sk(parent); + struct sock *next = NULL; + + /* accept_q is modified from child teardown paths too, so take a + * temporary reference before dropping the queue lock. + */ + spin_lock_bh(&bt->accept_q_lock); + + if (sk) { + if (bt_sk(sk)->parent != parent) + goto out; + + if (!list_is_last(&bt_sk(sk)->accept_q, &bt->accept_q)) { + next = &list_next_entry(bt_sk(sk), accept_q)->sk; + sock_hold(next); + } + } else if (!list_empty(&bt->accept_q)) { + next = &list_first_entry(&bt->accept_q, + struct bt_sock, accept_q)->sk; + sock_hold(next); + } + +out: + spin_unlock_bh(&bt->accept_q_lock); + return next; +} + struct sock *bt_accept_dequeue(struct sock *parent, struct socket *newsock) { - struct bt_sock *s, *n; - struct sock *sk; + struct sock *sk, *next; BT_DBG("parent %p", parent); restart: - list_for_each_entry_safe(s, n, &bt_sk(parent)->accept_q, accept_q) { - sk = (struct sock *)s; - + for (sk = bt_accept_get(parent, NULL); sk; sk = next) { /* Prevent early freeing of sk due to unlink and sock_kill */ - sock_hold(sk); lock_sock(sk); /* Check sk has not already been unlinked via * bt_accept_unlink() due to serialisation caused by sk locking */ - if (!bt_sk(sk)->parent) { + if (bt_sk(sk)->parent != parent) { BT_DBG("sk %p, already unlinked", sk); release_sock(sk); sock_put(sk); - /* Restart the loop as sk is no longer in the list - * and also avoid a potential infinite loop because - * list_for_each_entry_safe() is not thread safe. - */ goto restart; } + next = bt_accept_get(parent, sk); + /* sk is safely in the parent list so reduce reference count */ sock_put(sk); @@ -310,6 +341,8 @@ restart: sock_graft(sk, newsock); release_sock(sk); + if (next) + sock_put(next); return sk; } @@ -518,18 +551,28 @@ EXPORT_SYMBOL(bt_sock_stream_recvmsg); static inline __poll_t bt_accept_poll(struct sock *parent) { - struct bt_sock *s, *n; + struct bt_sock *bt = bt_sk(parent); + struct bt_sock *s; struct sock *sk; + __poll_t mask = 0; + + spin_lock_bh(&bt->accept_q_lock); + list_for_each_entry(s, &bt->accept_q, accept_q) { + int state; - list_for_each_entry_safe(s, n, &bt_sk(parent)->accept_q, accept_q) { sk = (struct sock *)s; - if (sk->sk_state == BT_CONNECTED || - (test_bit(BT_SK_DEFER_SETUP, &bt_sk(parent)->flags) && - sk->sk_state == BT_CONNECT2)) - return EPOLLIN | EPOLLRDNORM; - } + state = READ_ONCE(sk->sk_state); - return 0; + if (state == BT_CONNECTED || + (test_bit(BT_SK_DEFER_SETUP, &bt->flags) && + state == BT_CONNECT2)) { + mask = EPOLLIN | EPOLLRDNORM; + break; + } + } + spin_unlock_bh(&bt->accept_q_lock); + + return mask; } __poll_t bt_sock_poll(struct file *file, struct socket *sock,