From: Haiyang Zhang <haiyangz@microsoft.com>
Date: Wed, 23 Mar 2016 16:43:09 +0000 (-0700)
Subject: hv_netvsc: Fix accessing freed memory in netvsc_change_mtu()
X-Git-Tag: v4.6-rc1~38^2~4
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d212b4633c3a99561939f2d423eacf3263850bcd;p=platform%2Fkernel%2Flinux-exynos.git

hv_netvsc: Fix accessing freed memory in netvsc_change_mtu()

struct netvsc_device is freed in rndis_filter_device_remove(). So we save
the nvdev->num_chn into a temp variable for later usage.

(Please also include this patch into stable branch.)

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 08608499fa17..b8121eba33ff 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -858,6 +858,7 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 	struct netvsc_device *nvdev = hv_get_drvdata(hdev);
 	struct netvsc_device_info device_info;
 	int limit = ETH_DATA_LEN;
+	u32 num_chn;
 	int ret = 0;
 
 	if (nvdev == NULL || nvdev->destroy)
@@ -873,6 +874,8 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 	if (ret)
 		goto out;
 
+	num_chn = nvdev->num_chn;
+
 	nvdev->start_remove = true;
 	rndis_filter_device_remove(hdev);
 
@@ -883,7 +886,7 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 
 	memset(&device_info, 0, sizeof(device_info));
 	device_info.ring_size = ring_size;
-	device_info.num_chn = nvdev->num_chn;
+	device_info.num_chn = num_chn;
 	device_info.max_num_vrss_chns = max_num_vrss_chns;
 	rndis_filter_device_add(hdev, &device_info);