From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-sn1nam02on0134.outbound.protection.outlook.com ([104.47.36.134]:59648 "EHLO NAM02-SN1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728746AbeIBRXi (ORCPT ); Sun, 2 Sep 2018 13:23:38 -0400 From: Sasha Levin To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" CC: Jinbum Park , Jens Axboe , Sasha Levin Subject: [PATCH AUTOSEL 4.14 55/89] pktcdvd: Fix possible Spectre-v1 for pkt_devs Date: Sun, 2 Sep 2018 13:07:17 +0000 Message-ID: <20180902064918.183387-55-alexander.levin@microsoft.com> References: <20180902064918.183387-1-alexander.levin@microsoft.com> In-Reply-To: <20180902064918.183387-1-alexander.levin@microsoft.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: From: Jinbum Park [ Upstream commit 55690c07b44a82cc3359ce0c233f4ba7d80ba145 ] User controls @dev_minor which to be used as index of pkt_devs. So, It can be exploited via Spectre-like attack. (speculative execution) This kind of attack leaks address of pkt_devs, [1] It leads an attacker to bypass security mechanism such as KASLR. So sanitize @dev_minor before using it to prevent attack. [1] https://github.com/jinb-park/linux-exploit/ tree/master/exploit-remaining-spectre-gadget/leak_pkt_devs.c Signed-off-by: Jinbum Park Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/pktcdvd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c index 531a0915066b..11ec92e47455 100644 --- a/drivers/block/pktcdvd.c +++ b/drivers/block/pktcdvd.c @@ -67,7 +67,7 @@ #include #include #include - +#include #include =20 #define DRIVER_NAME "pktcdvd" @@ -2231,6 +2231,8 @@ static struct pktcdvd_device *pkt_find_dev_from_minor= (unsigned int dev_minor) { if (dev_minor >=3D MAX_WRITERS) return NULL; + + dev_minor =3D array_index_nospec(dev_minor, MAX_WRITERS); return pkt_devs[dev_minor]; } =20 --=20 2.17.1