Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752923AbdHRNcf (ORCPT ); Fri, 18 Aug 2017 09:32:35 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55550 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752832AbdHRNPu (ORCPT ); Fri, 18 Aug 2017 09:15:50 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Tejun Heo" , "Martin K. Petersen" , "Christoph Hellwig" Date: Fri, 18 Aug 2017 14:13:20 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 092/134] libata: reject passthrough WRITE SAME requests In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1464 Lines: 43 3.16.47-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Hellwig commit c6ade20f5e50e188d20b711a618b20dd1d50457e upstream. The WRITE SAME to TRIM translation rewrites the DATA OUT buffer. While the SCSI code accomodates for this by passing a read-writable buffer userspace applications don't cater for this behavior. In fact it can be used to rewrite e.g. a readonly file through mmap and should be considered as a security fix. Signed-off-by: Christoph Hellwig Reviewed-by: Martin K. Petersen Signed-off-by: Tejun Heo [bwh: Backported to 3.16: - Open-code blk_rq_is_passthrough() - We don't distinguish which field is invaid so goto invalid_fld - Adjust context] Signed-off-by: Ben Hutchings --- drivers/ata/libata-scsi.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -3097,6 +3097,14 @@ static unsigned int ata_scsi_write_same_ if (unlikely(!dev->dma_mode)) goto invalid_fld; + /* + * We only allow sending this command through the block layer, + * as it modifies the DATA OUT buffer, which would corrupt user + * memory for SG_IO commands. + */ + if (unlikely(scmd->request->cmd_type != REQ_TYPE_FS)) + goto invalid_fld; + if (unlikely(scmd->cmd_len < 16)) goto invalid_fld; scsi_16_lba_len(cdb, &block, &n_block);