[PATCH 3.18 13/19] scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE

Path	csiph.com!aioe.org!bofh.it!news.nic.it!robomod
From	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	[PATCH 3.18 13/19] scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE
Date	Tue, 12 Sep 2017 19:00:02 +0200
Message-ID	<uoWHw-3KO-33@gated-at.bofh.it> (permalink)
References	<uoWHv-3KO-11@gated-at.bofh.it>
X-Mailer	git-send-email 2.14.1
User-Agent	quilt/0.65
MIME-Version	1.0
Content-Type	text/plain; charset=UTF-8
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	60
Organization	linux.* mail to news gateway
X-Original-Cc	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, stable@vger.kernel.org, Todd Poynor <toddpoynor@google.com>, Douglas Gilbert <dgilbert@interlog.com>, "Martin K. Petersen" <martin.petersen@oracle.com>
X-Original-Date	Tue, 12 Sep 2017 09:54:49 -0700
X-Original-Message-ID	<20170912165016.702174112@linuxfoundation.org>
X-Original-References	<20170912165016.208029904@linuxfoundation.org>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1731010

Show key headers only | View raw

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Todd Poynor <toddpoynor@google.com>

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 <toddpoynor@google.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/scsi/sg.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1295,6 +1295,7 @@ 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;
@@ -1305,8 +1306,11 @@ 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);
@@ -1320,7 +1324,9 @@ 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

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

[PATCH 3.18 13/19] scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:00 +0200

csiph-web