Crash in netvsc_send() is observed when netvsc device is re-created on
mtu change/set channels. The crash is caused by dereferencing of NULL
channel pointer which comes from chn_table. The root cause is a mixture
of two facts:
- we set nvdev pointer in net_device_context in alloc_net_device()
before we populate chn_table.
- we populate chn_table[0] only.
The issue could be papered over by checking channel != NULL in
netvsc_send() but populating the whole chn_table and writing the
nvdev pointer afterwards seems more appropriate.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
drivers/net/hyperv/netvsc.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 96b3c32..719cb35 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -60,11 +60,9 @@ void netvsc_switch_datapath(struct net_device *ndev, bool vf)
}
-static struct netvsc_device *alloc_net_device(struct hv_device *device)
+static struct netvsc_device *alloc_net_device(void)
{
struct netvsc_device *net_device;
- struct net_device *ndev = hv_get_drvdata(device);
- struct net_device_context *net_device_ctx = netdev_priv(ndev);
net_device = kzalloc(sizeof(struct netvsc_device), GFP_KERNEL);
if (!net_device)
@@ -86,8 +84,6 @@ static struct netvsc_device *alloc_net_device(struct hv_device *device)
net_device->vf_netdev = NULL;
net_device->vf_inject = false;
- net_device_ctx->nvdev = net_device;
-
return net_device;
}
@@ -1240,20 +1236,19 @@ void netvsc_channel_cb(void *context)
*/
int netvsc_device_add(struct hv_device *device, void *additional_info)
{
- int ret = 0;
+ int i, ret = 0;
int ring_size =
((struct netvsc_device_info *)additional_info)->ring_size;
struct netvsc_device *net_device;
- struct net_device *ndev;
+ struct net_device *ndev = hv_get_drvdata(device);
+ struct net_device_context *net_device_ctx = netdev_priv(ndev);
- net_device = alloc_net_device(device);
+ net_device = alloc_net_device();
if (!net_device)
return -ENOMEM;
net_device->ring_size = ring_size;
- ndev = hv_get_drvdata(device);
-
/* Initialize the NetVSC channel extension */
init_completion(&net_device->channel_init_wait);
@@ -1272,7 +1267,19 @@ int netvsc_device_add(struct hv_device *device, void *additional_info)
/* Channel is opened */
pr_info("hv_netvsc channel opened successfully\n");
- net_device->chn_table[0] = device->channel;
+ /* If we're reopening the device we may have multiple queues, fill the
+ * chn_table with the default channel to use it before subchannels are
+ * opened.
+ */
+ for (i = 0; i < VRSS_CHANNEL_MAX; i++)
+ net_device->chn_table[i] = device->channel;
+
+ /* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is
+ * populated.
+ */
+ wmb();
+
+ net_device_ctx->nvdev = net_device;
/* Connect with the NetVsp */
ret = netvsc_connect_vsp(device);
--
2.5.5
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