From d0ddcea59aa9406e9fac5ca1809a77f60a4bc9d9 Mon Sep 17 00:00:00 2001 From: Josh Boyer 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 Reviewed-by: Sudeep Dutt Signed-off-by: Ashutosh Dixit Cc: stable Signed-off-by: Greg Kroah-Hartman Signed-off-by: Josh Boyer --- 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