From patchwork Fri Sep 14 18:52:49 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tyler Hicks X-Patchwork-Id: 970039 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=canonical.com Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 42Bl620Vt5z9s3x; Sat, 15 Sep 2018 04:53:30 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1g0tDX-0005Sn-A7; Fri, 14 Sep 2018 18:53:23 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.86_2) (envelope-from ) id 1g0tDV-0005RK-B6 for kernel-team@lists.ubuntu.com; Fri, 14 Sep 2018 18:53:21 +0000 Received: from 2.general.tyhicks.us.vpn ([10.172.64.53] helo=sec.ubuntu-ci) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1g0tDU-0006yb-RH; Fri, 14 Sep 2018 18:53:21 +0000 From: Tyler Hicks To: kernel-team@lists.ubuntu.com Subject: [PATCH 3/3] scsi: sg: recheck MMAP_IO request length with lock held Date: Fri, 14 Sep 2018 18:52:49 +0000 Message-Id: <1536951169-22810-4-git-send-email-tyhicks@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1536951169-22810-1-git-send-email-tyhicks@canonical.com> References: <1536951169-22810-1-git-send-email-tyhicks@canonical.com> X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Todd Poynor Commit 1bc0eb044615 ("scsi: sg: protect accesses to 'reserved' page array") adds needed concurrency protection for the "reserve" buffer. Some checks that are initially made outside the lock are replicated once the lock is taken to ensure the checks and resulting decisions are made using consistent state. The check that a request with flag SG_FLAG_MMAP_IO set fits in the reserve buffer also needs to be performed again under the lock to ensure the reserve buffer length compared against matches the value in effect when the request is linked to the reserve buffer. An -ENOMEM should be returned in this case, instead of switching over to an indirect buffer as for non-MMAP_IO requests. Signed-off-by: Todd Poynor Acked-by: Douglas Gilbert Signed-off-by: Martin K. Petersen CVE-2016-9576 (cherry picked from commit 8d26f491116feaa0b16de370b6a7ba40a40fa0b4) Signed-off-by: Tyler Hicks --- drivers/scsi/sg.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 42e5a140ada5..7b99026238eb 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -1703,9 +1703,12 @@ static int sg_start_req(Sg_request *srp, unsigned char *cmd) !sfp->res_in_use) { sfp->res_in_use = 1; sg_link_reserve(sfp, srp, dxfer_len); - } else if ((hp->flags & SG_FLAG_MMAP_IO) && sfp->res_in_use) { + } else if (hp->flags & SG_FLAG_MMAP_IO) { + res = -EBUSY; /* sfp->res_in_use == 1 */ + if (dxfer_len > rsv_schp->bufflen) + res = -ENOMEM; mutex_unlock(&sfp->f_mutex); - return -EBUSY; + return res; } else { res = sg_build_indirect(req_schp, sfp, dxfer_len); if (res) {