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	netvsc: fix use after free on module removal
The NAPI data structure is embedded in the netvsc_device structure and is freed when device is closed. There is still a reference (in NAPI list) to this which causes a crash in netif_napi_del when device is removed. Fix by managing NAPI instances correctly. Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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					 2 changed files with 11 additions and 7 deletions
				
			
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			@ -584,8 +584,9 @@ void netvsc_device_remove(struct hv_device *device)
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	/* Now, we can close the channel safely */
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	vmbus_close(device->channel);
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	/* And dissassociate NAPI context from device */
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	for (i = 0; i < net_device->num_chn; i++)
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		napi_disable(&net_device->chan_table[i].napi);
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		netif_napi_del(&net_device->chan_table[i].napi);
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	/* Release all resources */
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	free_netvsc_device_rcu(net_device);
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			@ -1320,8 +1321,6 @@ int netvsc_device_add(struct hv_device *device,
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		struct netvsc_channel *nvchan = &net_device->chan_table[i];
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		nvchan->channel = device->channel;
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		netif_napi_add(ndev, &nvchan->napi,
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			       netvsc_poll, NAPI_POLL_WEIGHT);
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	}
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	/* Open the channel */
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			@ -1339,6 +1338,8 @@ int netvsc_device_add(struct hv_device *device,
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	netdev_dbg(ndev, "hv_netvsc channel opened successfully\n");
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	/* Enable NAPI handler for init callbacks */
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	netif_napi_add(ndev, &net_device->chan_table[0].napi,
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		       netvsc_poll, NAPI_POLL_WEIGHT);
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	napi_enable(&net_device->chan_table[0].napi);
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	/* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is
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			@ -1357,7 +1358,7 @@ int netvsc_device_add(struct hv_device *device,
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	return ret;
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close:
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	napi_disable(&net_device->chan_table[0].napi);
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	netif_napi_del(&net_device->chan_table[0].napi);
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	/* Now, we can close the channel safely */
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	vmbus_close(device->channel);
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			@ -1009,13 +1009,16 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
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	/* Set the channel before opening.*/
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	nvchan->channel = new_sc;
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	netif_napi_add(ndev, &nvchan->napi,
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		       netvsc_poll, NAPI_POLL_WEIGHT);
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	ret = vmbus_open(new_sc, nvscdev->ring_size * PAGE_SIZE,
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			 nvscdev->ring_size * PAGE_SIZE, NULL, 0,
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			 netvsc_channel_cb, nvchan);
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	napi_enable(&nvchan->napi);
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	if (ret == 0)
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		napi_enable(&nvchan->napi);
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	else
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		netdev_err(ndev, "sub channel open failed (%d)\n", ret);
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	if (refcount_dec_and_test(&nvscdev->sc_offered))
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		complete(&nvscdev->channel_init_wait);
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