Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53AD2C433F5 for ; Wed, 24 Nov 2021 12:02:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241967AbhKXMFx (ORCPT ); Wed, 24 Nov 2021 07:05:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:60032 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235056AbhKXMEp (ORCPT ); Wed, 24 Nov 2021 07:04:45 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0678A6101D; Wed, 24 Nov 2021 12:01:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637755295; bh=UB43MWsnVoJwanemmwAvkG+DDaJyVuj66qqOR24jbhE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FPf18D+QeIyZpbUaQViHASFOb6wup2XGYXXaPxnVyNXgG3HCfdZzXPXF3tKjjhRLV FrALyTKi1bH3h31iISjiF2VzL4xWXeTz/g7HQBoQgSrr3L4eDMUgzpLgIN3jdooDnk 5YIB2869c2lFbIgbIjqIdOSTTpXDsJ3207wM5wm8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Takashi Iwai , Marcel Holtmann , Sasha Levin Subject: [PATCH 4.4 042/162] Bluetooth: sco: Fix lock_sock() blockage by memcpy_from_msg() Date: Wed, 24 Nov 2021 12:55:45 +0100 Message-Id: <20211124115659.705715200@linuxfoundation.org> X-Mailer: git-send-email 2.34.0 In-Reply-To: <20211124115658.328640564@linuxfoundation.org> References: <20211124115658.328640564@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Takashi Iwai [ Upstream commit 99c23da0eed4fd20cae8243f2b51e10e66aa0951 ] The sco_send_frame() also takes lock_sock() during memcpy_from_msg() call that may be endlessly blocked by a task with userfaultd technique, and this will result in a hung task watchdog trigger. Just like the similar fix for hci_sock_sendmsg() in commit 92c685dc5de0 ("Bluetooth: reorganize functions..."), this patch moves the memcpy_from_msg() out of lock_sock() for addressing the hang. This should be the last piece for fixing CVE-2021-3640 after a few already queued fixes. Signed-off-by: Takashi Iwai Signed-off-by: Marcel Holtmann Signed-off-by: Sasha Levin --- net/bluetooth/sco.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index 701d230fb9cf6..b9d0d1d6a4be1 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -269,7 +269,8 @@ done: return err; } -static int sco_send_frame(struct sock *sk, struct msghdr *msg, int len) +static int sco_send_frame(struct sock *sk, void *buf, int len, + unsigned int msg_flags) { struct sco_conn *conn = sco_pi(sk)->conn; struct sk_buff *skb; @@ -281,15 +282,11 @@ static int sco_send_frame(struct sock *sk, struct msghdr *msg, int len) BT_DBG("sk %p len %d", sk, len); - skb = bt_skb_send_alloc(sk, len, msg->msg_flags & MSG_DONTWAIT, &err); + skb = bt_skb_send_alloc(sk, len, msg_flags & MSG_DONTWAIT, &err); if (!skb) return err; - if (memcpy_from_msg(skb_put(skb, len), msg, len)) { - kfree_skb(skb); - return -EFAULT; - } - + memcpy(skb_put(skb, len), buf, len); hci_send_sco(conn->hcon, skb); return len; @@ -700,6 +697,7 @@ static int sco_sock_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) { struct sock *sk = sock->sk; + void *buf; int err; BT_DBG("sock %p, sk %p", sock, sk); @@ -711,14 +709,24 @@ static int sco_sock_sendmsg(struct socket *sock, struct msghdr *msg, if (msg->msg_flags & MSG_OOB) return -EOPNOTSUPP; + buf = kmalloc(len, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + if (memcpy_from_msg(buf, msg, len)) { + kfree(buf); + return -EFAULT; + } + lock_sock(sk); if (sk->sk_state == BT_CONNECTED) - err = sco_send_frame(sk, msg, len); + err = sco_send_frame(sk, buf, len, msg->msg_flags); else err = -ENOTCONN; release_sock(sk); + kfree(buf); return err; } -- 2.33.0