From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 600773D9056; Wed, 8 Apr 2026 18:53:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775674438; cv=none; b=F3w6nHF2c5lGKohux0V6bXkE7DafqA2Xrh0SJlAWLKpbQyZF87fswVCw34JjYhNGGvQmrhrleK7XyM6iqBG+KaLIiDu5NPxhMUt2Kj+KoYkDlhedW89XkOqooLNM9gOgHs9aH3bxd8elipXXP45jTV06d/2upWOZCATR7O71CLw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775674438; c=relaxed/simple; bh=6pNviJzoNI5J8A/17vy0x5TTcrUHU3/j1Zelo2bKa/g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DP/5kN08w+K1+wyv7apY8kLRJMVQ4/COWH6ixoovz+Pr98nvqbPQIbT/Ue3aFxFxGJVIghPTuXuJfaMWH0R3iEV7rS5oir5j8kd6NzNbxXRD0Ey2S/W3hxgO78khf7R2Ne5vKBM5ZjEaBroGFPZRcLRuIAaHTb67zGBufqSNh9E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fXN2xLfL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fXN2xLfL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9B03C19421; Wed, 8 Apr 2026 18:53:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775674438; bh=6pNviJzoNI5J8A/17vy0x5TTcrUHU3/j1Zelo2bKa/g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fXN2xLfL0sVCq2Hdv/V7jE6NT0F9lE4lLvwbZxxM50YwPt3WCa9QoR9F9+IuScNeh fkoVv0aQtP7F3gkYLonDXPOrrHoWnpasLJyQnOQ7XTBrpSKCu93BKGX6bVDueCXGsT XU68hUIyyEtiUMzSxD1n7jOFO5ln9iZahSKwjxAQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Cen Zhang , Luiz Augusto von Dentz , Sasha Levin Subject: [PATCH 6.19 096/311] Bluetooth: SCO: fix race conditions in sco_sock_connect() Date: Wed, 8 Apr 2026 20:01:36 +0200 Message-ID: <20260408175942.999022721@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408175939.393281918@linuxfoundation.org> References: <20260408175939.393281918@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cen Zhang [ Upstream commit 8a5b0135d4a5d9683203a3d9a12a711ccec5936b ] sco_sock_connect() checks sk_state and sk_type without holding the socket lock. Two concurrent connect() syscalls on the same socket can both pass the check and enter sco_connect(), leading to use-after-free. The buggy scenario involves three participants and was confirmed with additional logging instrumentation: Thread A (connect): HCI disconnect: Thread B (connect): sco_sock_connect(sk) sco_sock_connect(sk) sk_state==BT_OPEN sk_state==BT_OPEN (pass, no lock) (pass, no lock) sco_connect(sk): sco_connect(sk): hci_dev_lock hci_dev_lock hci_connect_sco <- blocked -> hcon1 sco_conn_add->conn1 lock_sock(sk) sco_chan_add: conn1->sk = sk sk->conn = conn1 sk_state=BT_CONNECT release_sock hci_dev_unlock hci_dev_lock sco_conn_del: lock_sock(sk) sco_chan_del: sk->conn=NULL conn1->sk=NULL sk_state= BT_CLOSED SOCK_ZAPPED release_sock hci_dev_unlock (unblocked) hci_connect_sco -> hcon2 sco_conn_add -> conn2 lock_sock(sk) sco_chan_add: sk->conn=conn2 sk_state= BT_CONNECT // zombie sk! release_sock hci_dev_unlock Thread B revives a BT_CLOSED + SOCK_ZAPPED socket back to BT_CONNECT. Subsequent cleanup triggers double sock_put() and use-after-free. Meanwhile conn1 is leaked as it was orphaned when sco_conn_del() cleared the association. Fix this by: - Moving lock_sock() before the sk_state/sk_type checks in sco_sock_connect() to serialize concurrent connect attempts - Fixing the sk_type != SOCK_SEQPACKET check to actually return the error instead of just assigning it - Adding a state re-check in sco_connect() after lock_sock() to catch state changes during the window between the locks - Adding sco_pi(sk)->conn check in sco_chan_add() to prevent double-attach of a socket to multiple connections - Adding hci_conn_drop() on sco_chan_add failure to prevent HCI connection leaks Fixes: 9a8ec9e8ebb5 ("Bluetooth: SCO: Fix possible circular locking dependency on sco_connect_cfm") Signed-off-by: Cen Zhang Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- net/bluetooth/sco.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index 6741b067d28b5..a446844354a18 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -298,7 +298,7 @@ static int sco_chan_add(struct sco_conn *conn, struct sock *sk, int err = 0; sco_conn_lock(conn); - if (conn->sk) + if (conn->sk || sco_pi(sk)->conn) err = -EBUSY; else __sco_chan_add(conn, sk, parent); @@ -353,9 +353,20 @@ static int sco_connect(struct sock *sk) lock_sock(sk); + /* Recheck state after reacquiring the socket lock, as another + * thread may have changed it (e.g., closed the socket). + */ + if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) { + release_sock(sk); + hci_conn_drop(hcon); + err = -EBADFD; + goto unlock; + } + err = sco_chan_add(conn, sk, NULL); if (err) { release_sock(sk); + hci_conn_drop(hcon); goto unlock; } @@ -656,13 +667,18 @@ static int sco_sock_connect(struct socket *sock, struct sockaddr_unsized *addr, addr->sa_family != AF_BLUETOOTH) return -EINVAL; - if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) + lock_sock(sk); + + if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) { + release_sock(sk); return -EBADFD; + } - if (sk->sk_type != SOCK_SEQPACKET) - err = -EINVAL; + if (sk->sk_type != SOCK_SEQPACKET) { + release_sock(sk); + return -EINVAL; + } - lock_sock(sk); /* Set destination address and psm */ bacpy(&sco_pi(sk)->dst, &sa->sco_bdaddr); release_sock(sk); -- 2.53.0