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| author |   Vitaly Kuznetsov <vkuznets@redhat.com> | 2016-10-19 15:53:01 +0200 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2016-10-21 11:27:31 -0400 |
| commit | e8f0a89cd7591c5d4eb7c77833af865b4db356b7 (patch) | |
| tree | 3dc3e1a0ff45a0b2182ead62097b19799a4d8305 | |
| parent | Merge branch 'MTU-core-range-checking-more' (diff) | |
| download | linux-dev-e8f0a89cd7591c5d4eb7c77833af865b4db356b7.tar.xz linux-dev-e8f0a89cd7591c5d4eb7c77833af865b4db356b7.zip | |
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.c | 7 |
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; |