From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8FC70C433DF for ; Tue, 9 Jun 2020 18:10:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69BBC2068D for ; Tue, 9 Jun 2020 18:10:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388563AbgFISKW (ORCPT ); Tue, 9 Jun 2020 14:10:22 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41376 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388159AbgFISF6 (ORCPT ); Tue, 9 Jun 2020 14:05:58 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1jiidG-0001pL-CH; Tue, 09 Jun 2020 19:05:54 +0100 Received: from ben by deadeye with local (Exim 4.94) (envelope-from ) id 1jiidF-006Vvr-A4; Tue, 09 Jun 2020 19:05:53 +0100 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, Denis Kirjanov , "Greg Kroah-Hartman" , "Douglas Gilbert" , "Todd Poynor" , "Martin K. Petersen" Date: Tue, 09 Jun 2020 19:04:19 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 28/61] scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.85-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Todd Poynor commit 6a8dadcca81fceff9976e8828cceb072873b7bd5 upstream. Take f_mutex around mmap() processing to protect against races with the SG_SET_RESERVED_SIZE ioctl. Ensure the reserve buffer length remains consistent during the mapping operation, and set the "mmap called" flag to prevent further changes to the reserved buffer size as an atomic operation with the mapping. [mkp: fixed whitespace] Signed-off-by: Todd Poynor Acked-by: Douglas Gilbert Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/scsi/sg.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -1310,6 +1310,7 @@ sg_mmap(struct file *filp, struct vm_are unsigned long req_sz, len, sa; Sg_scatter_hold *rsv_schp; int k, length; + int ret = 0; if ((!filp) || (!vma) || (!(sfp = (Sg_fd *) filp->private_data))) return -ENXIO; @@ -1319,8 +1320,11 @@ sg_mmap(struct file *filp, struct vm_are if (vma->vm_pgoff) return -EINVAL; /* want no offset */ rsv_schp = &sfp->reserve; - if (req_sz > rsv_schp->bufflen) - return -ENOMEM; /* cannot map more than reserved buffer */ + mutex_lock(&sfp->f_mutex); + if (req_sz > rsv_schp->bufflen) { + ret = -ENOMEM; /* cannot map more than reserved buffer */ + goto out; + } sa = vma->vm_start; length = 1 << (PAGE_SHIFT + rsv_schp->page_order); @@ -1334,7 +1338,9 @@ sg_mmap(struct file *filp, struct vm_are vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP; vma->vm_private_data = sfp; vma->vm_ops = &sg_mmap_vm_ops; - return 0; +out: + mutex_unlock(&sfp->f_mutex); + return ret; } static void