> -----Original Message-----
> From: Mohammed Gamal <mga...@redhat.com>
> Sent: Wednesday, September 26, 2018 12:34 PM
> To: Stephen Hemminger <sthem...@microsoft.com>; net...@vger.kernel.org
> Cc: KY Srinivasan <k...@microsoft.com>; Haiyang Zhang
> <haiya...@microsoft.com>; vkuznets <vkuzn...@redhat.com>;
> ot...@redhat.com; cavery <cav...@redhat.com>; linux-
> ker...@vger.kernel.org; de...@linuxdriverproject.org; Mohammed Gamal
> <mga...@redhat.com>
> Subject: [PATCH] hv_netvsc: Make sure out channel is fully opened on send
>
> Dring high network traffic changes to network interface parameters such as
> number of channels or MTU can cause a kernel panic with a NULL pointer
> dereference. This is due to netvsc_device_remove() being called and
> deallocating the channel ring buffers, which can then be accessed by
> netvsc_send_pkt() before they're allocated on calling
> netvsc_device_add()
>
> The patch fixes this problem by checking the channel state and returning
> ENODEV if not yet opened. We also move the call to hv_ringbuf_avail_percent()
> which may access the uninitialized ring buffer.
>
> Signed-off-by: Mohammed Gamal <mga...@redhat.com>
> ---
> drivers/net/hyperv/netvsc.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index
> fe01e14..75f1b31 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -825,7 +825,12 @@ static inline int netvsc_send_pkt(
> struct netdev_queue *txq = netdev_get_tx_queue(ndev, packet->q_idx);
> u64 req_id;
> int ret;
> - u32 ring_avail = hv_get_avail_to_write_percent(&out_channel-
> >outbound);
> + u32 ring_avail;
> +
> + if (out_channel->state != CHANNEL_OPENED_STATE)
> + return -ENODEV;
> +
> + ring_avail = hv_get_avail_to_write_percent(&out_channel->outbound);
When you reproducing the NULL ptr panic, does your kernel include the following
patch?
hv_netvsc: common detach logic
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=7b2ee50c0cd513a176a26a71f2989facdd75bfea
We call netif_tx_disable(ndev) and netif_device_detach(ndev) before doing the
changes
on MTU or #channels. So there should be no call to start_xmit() when channel is
not ready.
If you see the check for CHANNEL_OPENED_STATE is still necessary on upstream
kernel (including
the patch " common detach logic "), we should debug further on the code and
find out the
root cause.
Thanks,
- Haiyang
_______________________________________________
devel mailing list
de...@linuxdriverproject.org
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
