From 72aaf646fb6b6f8f7befb44cbd5b1acd3bb5b483 Mon Sep 17 00:00:00 2001 From: Ashutosh Dixit Date: Wed, 27 Apr 2016 14:36:05 -0700 Subject: [PATCH] misc: mic: Fix for double fetch security bug in VOP driver commit 9bf292bfca94694a721449e3fd752493856710f6 upstream. 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 Reviewed-by: Sudeep Dutt Signed-off-by: Ashutosh Dixit Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: - Adjust filename, context - goto exit on failure] Signed-off-by: Ben Hutchings --- 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 7e1ef0ebbb800..dba3c19929db0 100644 --- a/drivers/misc/mic/host/mic_virtio.c +++ b/drivers/misc/mic/host/mic_virtio.c @@ -456,6 +456,11 @@ 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++) { -- 2.47.3