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received-spf: None (protection.outlook.com: microsoft.com does not designate permitted sender hosts) authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-message-info: NxWUb+2LlhA8/0fGrEmu1UbTdQg77wKvdZKgEi2jqsxdeHIda+QIrLi5F8dXODPIW8H6pLOyELBPQjrDEr1TAzwsJtNmYCDZlR9nIfBQqMakQqFkJasW1gEVz6yrLmYM7V7afXFLXiEP1dOUQX35tLD2gs1i70+kcLTPDK4eCican1agm4BbEuqKILlfA7T35H/4ol0oeGwBuosa3JiyMQj3kw8lfCrh7pzXrWe1VwqagB79I7x/In91n8XRAOXsq1bIYLDNKp3RjCuUWA6tOMpbtbwdzJGf7+FNtQCiAd2dwt8qjSwH9Y1Kz25pRXA82MTWe1DkGmpcZL69gCJUWBVQToRIoLfcHdvTpTGJDHE= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 10b23134-2385-4459-c0de-08d610d513d7 X-MS-Exchange-CrossTenant-originalarrivaltime: 02 Sep 2018 13:07:17.6257 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0503 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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