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 E9C3C15B998; Tue, 16 Jun 2026 15:52:22 +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=1781625144; cv=none; b=BhqPewi+Gw1YuKmRmEbN67O5KnawgtJmrvJZkwSfkYJnWUGRzWJqEEmhQ9C6XTCa5NAaNc74zK+5UjoTZgPwLIzFgPu99epr3cnoOoiwxdq9L6HfCqSgz99/RsmggceMP/VUKECV3cgFNFgUZH0AEKUBM8VVXpvau4BG8Lw8oq0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781625144; c=relaxed/simple; bh=eXwjPPxdbZdO+PKe2+OCZaXiFzAL1+/z6Y7En9F/scI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pA5cEDGnMHeW1/m+aEgToGIVHpElPOyEYd3aOVcmXx/IeV3ZHeX6UX4gZFGCyE1gPfPr+JCyxOo7SEQTetcrABbl2actx+A06oOz1twKBflFx5muqwzAPNU72nAnrSMNlndtVoHwoCkgWB6ZWfI7CL5MCR1hSFLEXoQ23eHndX8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cSnnEqXS; 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="cSnnEqXS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8EDE1F000E9; Tue, 16 Jun 2026 15:52:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781625142; bh=LVrcshrtwFWLNMav0HsKWO1ih+p3HrgE6RxN79MRcKc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=cSnnEqXSEnduGaGuKfeWZI8kCj/natvoTtKP0J7cyM1Cl039STrAezLjxwCJJBbgt K0zM4ANmp/LepD+fbf092MaR5moWbNudV4j7eMQnsQnx9mSZxkaNLQ5B0dss5AR3JX xe4UAAskzJ11sTbUhtx69pE8sv2mZmrctHIINaCM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zhang Cen , Luiz Augusto von Dentz , Sasha Levin Subject: [PATCH 6.18 042/325] Bluetooth: RFCOMM: hold listener socket in rfcomm_connect_ind() Date: Tue, 16 Jun 2026 20:27:18 +0530 Message-ID: <20260616145059.824204809@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145057.827196531@linuxfoundation.org> References: <20260616145057.827196531@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhang Cen [ Upstream commit 43c441edacf953b39517a44f5e5e10a93618b226 ] rfcomm_get_sock_by_channel() scans rfcomm_sk_list under the list lock, but returns the selected listener after dropping that lock without taking a reference. rfcomm_connect_ind() then locks the listener, queues a child socket on it, and may notify it after unlocking it. The buggy scenario involves two paths, with each column showing the order within that path: rfcomm_connect_ind(): listener close: 1. Find parent in 1. close() enters rfcomm_get_sock_by_channel() rfcomm_sock_release(). 2. Drop rfcomm_sk_list.lock 2. rfcomm_sock_shutdown() without pinning parent. closes the listener. 3. Call lock_sock(parent) and 3. rfcomm_sock_kill() bt_accept_enqueue(parent, unlinks and puts parent. sk, true). 4. Read parent flags and may 4. parent can be freed. call sk_state_change(). If close wins the race, parent can be freed before rfcomm_connect_ind() reaches lock_sock(), bt_accept_enqueue(), or the deferred-setup callback. Take a reference on the listener before leaving rfcomm_sk_list.lock. After lock_sock() succeeds, recheck that it is still in BT_LISTEN before queueing a child, cache the deferred-setup bit while the parent is locked, and drop the reference after the last parent use. KASAN reported a slab-use-after-free in lock_sock_nested() from rfcomm_connect_ind(), with the freeing stack going through rfcomm_sock_kill() and rfcomm_sock_release(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Zhang Cen Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- net/bluetooth/rfcomm/sock.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c index 3052436e9c6de5..2286efef62f5b6 100644 --- a/net/bluetooth/rfcomm/sock.c +++ b/net/bluetooth/rfcomm/sock.c @@ -122,7 +122,7 @@ static struct sock *__rfcomm_get_listen_sock_by_addr(u8 channel, bdaddr_t *src) } /* Find socket with channel and source bdaddr. - * Returns closest match. + * Returns closest match with an extra reference held. */ static struct sock *rfcomm_get_sock_by_channel(int state, u8 channel, bdaddr_t *src) { @@ -136,15 +136,25 @@ static struct sock *rfcomm_get_sock_by_channel(int state, u8 channel, bdaddr_t * if (rfcomm_pi(sk)->channel == channel) { /* Exact match. */ - if (!bacmp(&rfcomm_pi(sk)->src, src)) + if (!bacmp(&rfcomm_pi(sk)->src, src)) { + sock_hold(sk); break; + } /* Closest match */ - if (!bacmp(&rfcomm_pi(sk)->src, BDADDR_ANY)) + if (!bacmp(&rfcomm_pi(sk)->src, BDADDR_ANY)) { + if (sk1) + sock_put(sk1); + sk1 = sk; + sock_hold(sk1); + } } } + if (sk && sk1) + sock_put(sk1); + read_unlock(&rfcomm_sk_list.lock); return sk ? sk : sk1; @@ -940,6 +950,7 @@ int rfcomm_connect_ind(struct rfcomm_session *s, u8 channel, struct rfcomm_dlc * { struct sock *sk, *parent; bdaddr_t src, dst; + bool defer_setup = false; int result = 0; BT_DBG("session %p channel %d", s, channel); @@ -953,6 +964,11 @@ int rfcomm_connect_ind(struct rfcomm_session *s, u8 channel, struct rfcomm_dlc * lock_sock(parent); + if (parent->sk_state != BT_LISTEN) + goto done; + + defer_setup = test_bit(BT_SK_DEFER_SETUP, &bt_sk(parent)->flags); + /* Check for backlog size */ if (sk_acceptq_is_full(parent)) { BT_DBG("backlog full %d", parent->sk_ack_backlog); @@ -980,9 +996,11 @@ int rfcomm_connect_ind(struct rfcomm_session *s, u8 channel, struct rfcomm_dlc * done: release_sock(parent); - if (test_bit(BT_SK_DEFER_SETUP, &bt_sk(parent)->flags)) + if (defer_setup) parent->sk_state_change(parent); + sock_put(parent); + return result; } -- 2.53.0