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authorVitaly Kuznetsov <vkuznets@redhat.com>2016-10-19 16:53:01 +0300
committerDavid S. Miller <davem@davemloft.net>2016-10-21 18:27:31 +0300
commite8f0a89cd7591c5d4eb7c77833af865b4db356b7 (patch)
tree3dc3e1a0ff45a0b2182ead62097b19799a4d8305
parent9e58c5dc4be31f8cf3ff62d96f91c97af6f9d58e (diff)
downloadlinux-e8f0a89cd7591c5d4eb7c77833af865b4db356b7.tar.xz
hv_netvsc: fix a race between netvsc_send() and netvsc_init_buf()
Fix in commit 880988348270 ("hv_netvsc: set nvdev link after populating chn_table") turns out to be incomplete. A crash in netvsc_get_next_send_section() is observed on mtu change when the device is under load. The race I identified is: if we get to netvsc_send() after we set net_device_ctx->nvdev link in netvsc_device_add() but before we finish netvsc_connect_vsp()->netvsc_init_buf() send_section_map is not allocated and we crash. Unfortunately we can't set net_device_ctx->nvdev link after the netvsc_init_buf() call as during the negotiation we need to receive packets and on the receive path we check for it. It would probably be possible to split nvdev into a pair of nvdev_in and nvdev_out links and check them accordingly in get_outbound_net_device()/ get_inbound_net_device() but this looks like an overkill. Check that send_section_map is allocated in netvsc_send(). Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/hyperv/netvsc.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 720b5fa9e625..e2bfaac1801d 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -888,6 +888,13 @@ int netvsc_send(struct hv_device *device,
if (!net_device)
return -ENODEV;
+ /* We may race with netvsc_connect_vsp()/netvsc_init_buf() and get
+ * here before the negotiation with the host is finished and
+ * send_section_map may not be allocated yet.
+ */
+ if (!net_device->send_section_map)
+ return -EAGAIN;
+
out_channel = net_device->chn_table[q_idx];
packet->send_buf_index = NETVSC_INVALID_INDEX;