[PATCH net-next, 1/2] hv_netvsc: Fix accessing freed memory in netvsc_change_mtu()

[PATCH net-next, 1/2] hv_netvsc: Fix accessing freed memory in netvsc_change_mtu()

[Haiyang Zhang]

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>

---
 drivers/net/hyperv/netvsc_drv.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 0860849..b8121eb 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);
 
-- 
1.7.4.1

[PATCH net-next, 2/2] hv_netvsc: Fix the array sizes to be max supported channels

[Haiyang Zhang]

The VRSS_CHANNEL_MAX is the max number of channels supported by Hyper-V
hosts. We use it for the related array sizes instead of using NR_CPUS,
which may be set to several thousands.
This patch reduces possible memory allocation failures.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>

---
 drivers/net/hyperv/hyperv_net.h   |    7 ++++---
 drivers/net/hyperv/rndis_filter.c |    4 ++--
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index b4c6878..8b3bd8e 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -619,6 +619,7 @@ struct nvsp_message {
 #define NETVSC_PACKET_SIZE                      4096
 
 #define VRSS_SEND_TAB_SIZE 16
+#define VRSS_CHANNEL_MAX 64
 
 #define RNDIS_MAX_PKT_DEFAULT 8
 #define RNDIS_PKT_ALIGN_DEFAULT 8
@@ -700,13 +701,13 @@ struct netvsc_device {
 
 	struct net_device *ndev;
 
-	struct vmbus_channel *chn_table[NR_CPUS];
+	struct vmbus_channel *chn_table[VRSS_CHANNEL_MAX];
 	u32 send_table[VRSS_SEND_TAB_SIZE];
 	u32 max_chn;
 	u32 num_chn;
 	spinlock_t sc_lock; /* Protects num_sc_offered variable */
 	u32 num_sc_offered;
-	atomic_t queue_sends[NR_CPUS];
+	atomic_t queue_sends[VRSS_CHANNEL_MAX];
 
 	/* Holds rndis device info */
 	void *extension;
@@ -718,7 +719,7 @@ struct netvsc_device {
 	/* The sub channel callback buffer */
 	unsigned char *sub_cb_buf;
 
-	struct multi_send_data msd[NR_CPUS];
+	struct multi_send_data msd[VRSS_CHANNEL_MAX];
 	u32 max_pkt; /* max number of pkt in one send, e.g. 8 */
 	u32 pkt_align; /* alignment bytes, e.g. 8 */
 
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 47d07c5..d5a54da 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1113,9 +1113,9 @@ int rndis_filter_device_add(struct hv_device *dev,
 	if (ret || rsscap.num_recv_que < 2)
 		goto out;
 
-	num_rss_qs = min(device_info->max_num_vrss_chns, rsscap.num_recv_que);
+	net_device->max_chn = min_t(u32, VRSS_CHANNEL_MAX, rsscap.num_recv_que);
 
-	net_device->max_chn = rsscap.num_recv_que;
+	num_rss_qs = min(device_info->max_num_vrss_chns, net_device->max_chn);
 
 	/*
 	 * We will limit the VRSS channels to the number CPUs in the NUMA node
-- 
1.7.4.1