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 02E6547AF5F; Tue, 16 Jun 2026 17:39:25 +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=1781631566; cv=none; b=fE3VC1X7oBaVCxVIBbbqjWJtIiPYmEQ1TjzKQTfSrNHSzyAD8XWOWuazymj/30bAO5fBbmJQTcw/4LI146MUFNC7QVqgsvgmhrbCFl9rSI7U/rCRe9afis/gNb0tWevMEkkHUaZAhZtxgnsYFyfen6Wp6fpZyWo4whoYbQm5qEQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781631566; c=relaxed/simple; bh=KN9ah7mvsKMfMNkgvzzde4T5L7ayWlpPfUNIjJg0tYE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=J2eBDtYUiavvJKdA7b4aS+KvCibqpwVOdSo0vO6yupENgiCsONUf/BgLUrl44zwJmBbmTmggjAD31BjPD8HYUJSO0h26j8cGBUL1rmnazoJp0oSUJhfXs226cu9fiDAQLJBxcXshIP6E39vt7ts121NYIAgLVMK1UBseMr3Hh+w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LwxUMN23; 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="LwxUMN23" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A40F1F000E9; Tue, 16 Jun 2026 17:39:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781631564; bh=wT+CYkDKyfQDzcudA8eDnhZDWc/Q+IRFhlZ+MnEwuBA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LwxUMN23C6CHZU49+FMzx7fJDMR1uUofUGj4nhDPBnQ1T+OqgeTOFr0KvCxNdpfce Z/a6iBDpgpnN6zSunDJ64zyVsnEUcuYzR2noKQba6XrfvrGrb8KjAQYRkL2KU2pgF8 +2xX2iElvMwzaHr0WzbID1ry58Hsiq3calQFIOgA= 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 6.1 212/522] Bluetooth: RFCOMM: hold listener socket in rfcomm_connect_ind() Date: Tue, 16 Jun 2026 20:25:59 +0530 Message-ID: <20260616145135.967815166@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145125.307082728@linuxfoundation.org> References: <20260616145125.307082728@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 6.1-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 bc2b22c2b3aec7..d72cdcd2e2bb11 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; @@ -941,6 +951,7 @@ 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); @@ -954,6 +965,11 @@ 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); @@ -981,9 +997,11 @@ 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