From nobody Fri Dec 19 20:52:50 2025 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 A6CB4C32772 for ; Tue, 23 Aug 2022 09:29:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349404AbiHWJ3h (ORCPT ); Tue, 23 Aug 2022 05:29:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52444 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351151AbiHWJ0o (ORCPT ); Tue, 23 Aug 2022 05:26:44 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 50EBC91094; Tue, 23 Aug 2022 01:37:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EFA6F614C5; Tue, 23 Aug 2022 08:35:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3F7AC433D6; Tue, 23 Aug 2022 08:35:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661243745; bh=iJZpFLRwvDbeVZ/DqC+ffQrnPhgOnA1QgJ3ZxT8FJCc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qlUhYW5yUywWxAPe3aRgo57zi6dsA/Lkhu8eVBs39yzSROYjGIuD3bQYkuxOBnNz0 gkitNaRcBInZU5oINYX2eRF+6oZyqXlsuOMrz0ZJ//GeOoFNmBTyFrIuSVfooCcYcu 4WDQVcM2+5298Xu2uSNYyvYuAQ1y5ACK5NLbGA50= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, stable@kernel.org, Lee Jones , Luiz Augusto von Dentz Subject: [PATCH 4.14 001/229] Bluetooth: L2CAP: Fix use-after-free caused by l2cap_chan_put Date: Tue, 23 Aug 2022 10:22:42 +0200 Message-Id: <20220823080053.272976849@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080053.202747790@linuxfoundation.org> References: <20220823080053.202747790@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Luiz Augusto von Dentz commit d0be8347c623e0ac4202a1d4e0373882821f56b0 upstream. This fixes the following trace which is caused by hci_rx_work starting up *after* the final channel reference has been put() during sock_close() but *before* the references to the channel have been destroyed, so instead the code now rely on kref_get_unless_zero/l2cap_chan_hold_unless_zero to prevent referencing a channel that is about to be destroyed. refcount_t: increment on 0; use-after-free. BUG: KASAN: use-after-free in refcount_dec_and_test+0x20/0xd0 Read of size 4 at addr ffffffc114f5bf18 by task kworker/u17:14/705 CPU: 4 PID: 705 Comm: kworker/u17:14 Tainted: G S W 4.14.234-00003-g1fb6d0bd49a4-dirty #28 Hardware name: Qualcomm Technologies, Inc. SM8150 V2 PM8150 Google Inc. MSM sm8150 Flame DVT (DT) Workqueue: hci0 hci_rx_work Call trace: dump_backtrace+0x0/0x378 show_stack+0x20/0x2c dump_stack+0x124/0x148 print_address_description+0x80/0x2e8 __kasan_report+0x168/0x188 kasan_report+0x10/0x18 __asan_load4+0x84/0x8c refcount_dec_and_test+0x20/0xd0 l2cap_chan_put+0x48/0x12c l2cap_recv_frame+0x4770/0x6550 l2cap_recv_acldata+0x44c/0x7a4 hci_acldata_packet+0x100/0x188 hci_rx_work+0x178/0x23c process_one_work+0x35c/0x95c worker_thread+0x4cc/0x960 kthread+0x1a8/0x1c4 ret_from_fork+0x10/0x18 Cc: stable@kernel.org Reported-by: Lee Jones Signed-off-by: Luiz Augusto von Dentz Tested-by: Lee Jones Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman --- include/net/bluetooth/l2cap.h | 1=20 net/bluetooth/l2cap_core.c | 61 +++++++++++++++++++++++++++++++++----= ----- 2 files changed, 49 insertions(+), 13 deletions(-) --- a/include/net/bluetooth/l2cap.h +++ b/include/net/bluetooth/l2cap.h @@ -798,6 +798,7 @@ enum { }; =20 void l2cap_chan_hold(struct l2cap_chan *c); +struct l2cap_chan *l2cap_chan_hold_unless_zero(struct l2cap_chan *c); void l2cap_chan_put(struct l2cap_chan *c); =20 static inline void l2cap_chan_lock(struct l2cap_chan *chan) --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -113,7 +113,8 @@ static struct l2cap_chan *__l2cap_get_ch } =20 /* Find channel with given SCID. - * Returns locked channel. */ + * Returns a reference locked channel. + */ static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn, u16 cid) { @@ -121,15 +122,19 @@ static struct l2cap_chan *l2cap_get_chan =20 mutex_lock(&conn->chan_lock); c =3D __l2cap_get_chan_by_scid(conn, cid); - if (c) - l2cap_chan_lock(c); + if (c) { + /* Only lock if chan reference is not 0 */ + c =3D l2cap_chan_hold_unless_zero(c); + if (c) + l2cap_chan_lock(c); + } mutex_unlock(&conn->chan_lock); =20 return c; } =20 /* Find channel with given DCID. - * Returns locked channel. + * Returns a reference locked channel. */ static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn, u16 cid) @@ -138,8 +143,12 @@ static struct l2cap_chan *l2cap_get_chan =20 mutex_lock(&conn->chan_lock); c =3D __l2cap_get_chan_by_dcid(conn, cid); - if (c) - l2cap_chan_lock(c); + if (c) { + /* Only lock if chan reference is not 0 */ + c =3D l2cap_chan_hold_unless_zero(c); + if (c) + l2cap_chan_lock(c); + } mutex_unlock(&conn->chan_lock); =20 return c; @@ -164,8 +173,12 @@ static struct l2cap_chan *l2cap_get_chan =20 mutex_lock(&conn->chan_lock); c =3D __l2cap_get_chan_by_ident(conn, ident); - if (c) - l2cap_chan_lock(c); + if (c) { + /* Only lock if chan reference is not 0 */ + c =3D l2cap_chan_hold_unless_zero(c); + if (c) + l2cap_chan_lock(c); + } mutex_unlock(&conn->chan_lock); =20 return c; @@ -491,6 +504,16 @@ void l2cap_chan_hold(struct l2cap_chan * kref_get(&c->kref); } =20 +struct l2cap_chan *l2cap_chan_hold_unless_zero(struct l2cap_chan *c) +{ + BT_DBG("chan %p orig refcnt %u", c, kref_read(&c->kref)); + + if (!kref_get_unless_zero(&c->kref)) + return NULL; + + return c; +} + void l2cap_chan_put(struct l2cap_chan *c) { BT_DBG("chan %p orig refcnt %d", c, kref_read(&c->kref)); @@ -1803,7 +1826,10 @@ static struct l2cap_chan *l2cap_global_c src_match =3D !bacmp(&c->src, src); dst_match =3D !bacmp(&c->dst, dst); if (src_match && dst_match) { - l2cap_chan_hold(c); + c =3D l2cap_chan_hold_unless_zero(c); + if (!c) + continue; + read_unlock(&chan_list_lock); return c; } @@ -1818,7 +1844,7 @@ static struct l2cap_chan *l2cap_global_c } =20 if (c1) - l2cap_chan_hold(c1); + c1 =3D l2cap_chan_hold_unless_zero(c1); =20 read_unlock(&chan_list_lock); =20 @@ -4204,6 +4230,7 @@ static inline int l2cap_config_req(struc =20 unlock: l2cap_chan_unlock(chan); + l2cap_chan_put(chan); return err; } =20 @@ -4316,6 +4343,7 @@ static inline int l2cap_config_rsp(struc =20 done: l2cap_chan_unlock(chan); + l2cap_chan_put(chan); return err; } =20 @@ -5044,6 +5072,7 @@ send_move_response: l2cap_send_move_chan_rsp(chan, result); =20 l2cap_chan_unlock(chan); + l2cap_chan_put(chan); =20 return 0; } @@ -5136,6 +5165,7 @@ static void l2cap_move_continue(struct l } =20 l2cap_chan_unlock(chan); + l2cap_chan_put(chan); } =20 static void l2cap_move_fail(struct l2cap_conn *conn, u8 ident, u16 icid, @@ -5165,6 +5195,7 @@ static void l2cap_move_fail(struct l2cap l2cap_send_move_chan_cfm(chan, L2CAP_MC_UNCONFIRMED); =20 l2cap_chan_unlock(chan); + l2cap_chan_put(chan); } =20 static int l2cap_move_channel_rsp(struct l2cap_conn *conn, @@ -5228,6 +5259,7 @@ static int l2cap_move_channel_confirm(st l2cap_send_move_chan_cfm_rsp(conn, cmd->ident, icid); =20 l2cap_chan_unlock(chan); + l2cap_chan_put(chan); =20 return 0; } @@ -5263,6 +5295,7 @@ static inline int l2cap_move_channel_con } =20 l2cap_chan_unlock(chan); + l2cap_chan_put(chan); =20 return 0; } @@ -5635,12 +5668,11 @@ static inline int l2cap_le_credits(struc if (credits > max_credits) { BT_ERR("LE credits overflow"); l2cap_send_disconn_req(chan, ECONNRESET); - l2cap_chan_unlock(chan); =20 /* Return 0 so that we don't trigger an unnecessary * command reject packet. */ - return 0; + goto unlock; } =20 chan->tx_credits +=3D credits; @@ -5651,7 +5683,9 @@ static inline int l2cap_le_credits(struc if (chan->tx_credits) chan->ops->resume(chan); =20 +unlock: l2cap_chan_unlock(chan); + l2cap_chan_put(chan); =20 return 0; } @@ -6949,6 +6983,7 @@ drop: =20 done: l2cap_chan_unlock(chan); + l2cap_chan_put(chan); } =20 static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm, @@ -7353,7 +7388,7 @@ static struct l2cap_chan *l2cap_global_f if (src_type !=3D c->src_type) continue; =20 - l2cap_chan_hold(c); + c =3D l2cap_chan_hold_unless_zero(c); read_unlock(&chan_list_lock); return c; }