Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752110AbdILQ5W (ORCPT ); Tue, 12 Sep 2017 12:57:22 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48324 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752025AbdILQ5C (ORCPT ); Tue, 12 Sep 2017 12:57:02 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Todd Poynor , Douglas Gilbert , "Martin K. Petersen" Subject: [PATCH 4.4 19/31] scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE Date: Tue, 12 Sep 2017 09:56:14 -0700 Message-Id: <20170912165248.344606063@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170912165247.436880944@linuxfoundation.org> References: <20170912165247.436880944@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1882 Lines: 61 4.4-stable 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 --- drivers/scsi/sg.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -1254,6 +1254,7 @@ 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; @@ -1264,8 +1265,11 @@ 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); @@ -1279,7 +1283,9 @@ 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