From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mohammed Gamal Subject: [PATCH] hv_netvsc: Make sure out channel is fully opened on send Date: Tue, 13 Mar 2018 20:06:50 +0100 Message-ID: <1520968010-20733-1-git-send-email-mgamal@redhat.com> Cc: devel@linuxdriverproject.org, davem@davemloft.net, vkuznets@redhat.com, otubo@redhat.com, linux-kernel@vger.kernel.org, Mohammed Gamal To: netdev@vger.kernel.org, sthemmin@microsoft.com Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 --- drivers/net/hyperv/netvsc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index 0265d70..44a8358 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -757,7 +757,7 @@ 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_ringbuf_avail_percent(&out_channel->outbound); + u32 ring_avail; nvmsg.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT; if (skb) @@ -773,7 +773,7 @@ static inline int netvsc_send_pkt( req_id = (ulong)skb; - if (out_channel->rescind) + if (out_channel->rescind || out_channel->state != CHANNEL_OPENED_STATE) return -ENODEV; if (packet->page_buf_cnt) { @@ -791,6 +791,7 @@ static inline int netvsc_send_pkt( VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED); } + ring_avail = hv_ringbuf_avail_percent(&out_channel->outbound); if (ret == 0) { atomic_inc_return(&nvchan->queue_sends); -- 1.8.3.1