From d0ddcea59aa9406e9fac5ca1809a77f60a4bc9d9 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@fedoraproject.org>
Date: Tue, 28 Jun 2016 09:54:56 -0400
Subject: [PATCH] misc: mic: Fix for double fetch security bug in
mic_copy_dp_entry
commit 9bf292bfca94694a721449e3fd752493856710f6 upstream
The MIC 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.
[Backported to linux-4.5.y by Josh Boyer]
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>
Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
---
drivers/misc/mic/host/mic_virtio.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/misc/mic/host/mic_virtio.c b/drivers/misc/mic/host/mic_virtio.c
index 58b107a24a8b..7a64f5a619d6 100644
--- a/drivers/misc/mic/host/mic_virtio.c
+++ b/drivers/misc/mic/host/mic_virtio.c
@@ -555,6 +555,11 @@ static int mic_copy_dp_entry(struct mic_vdev *mvdev,
__func__, __LINE__, ret);
goto exit;
}
+ /* Ensure desc has not changed between the two reads */
+ if (memcmp(&dd, dd_config, sizeof(dd))) {
+ ret = -EINVAL;
+ goto exit;
+ }
vqconfig = mic_vq_config(dd_config);
for (i = 0; i < dd.num_vq; i++) {
--
2.5.5