patch "misc: mic: Fix for double fetch security bug in VOP driver" added to char-misc-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    misc: mic: Fix for double fetch security bug in VOP driver

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 82dc4afd7e65455464f0fc2fe6976efde54fe451 Mon Sep 17 00:00:00 2001
From: Ashutosh Dixit <ashutosh.dixit@intel.com>
Date: Wed, 27 Apr 2016 14:36:05 -0700
Subject: misc: mic: Fix for double fetch security bug in VOP driver

The MIC VOP driver does two successive reads from user space to read a
variable length data structure. Kernel memory corruption can result if
the data structure changes between the two reads. This patch disallows
the chance of this happening.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=116651
Reported by: Pengfei Wang <wpengfeinudt@gmail.com>
Reviewed-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/misc/mic/vop/vop_vringh.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/misc/mic/vop/vop_vringh.c b/drivers/misc/mic/vop/vop_vringh.c
index e94c7fb6712a..88e45234d527 100644
--- a/drivers/misc/mic/vop/vop_vringh.c
+++ b/drivers/misc/mic/vop/vop_vringh.c
@@ -945,6 +945,11 @@ static long vop_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
 			ret = -EFAULT;
 			goto free_ret;
 		}
+		/* Ensure desc has not changed between the two reads */
+		if (memcmp(&dd, dd_config, sizeof(dd))) {
+			ret = -EINVAL;
+			goto free_ret;
+		}
 		mutex_lock(&vdev->vdev_mutex);
 		mutex_lock(&vi->vop_mutex);
 		ret = vop_virtio_add_device(vdev, dd_config);
-- 
2.8.0