From: Michael Chan michael.chan@broadcom.com
stable inclusion from linux-4.19.215 commit 02302cbd52264337630a32848ac03648648e9685
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commit 0c57eeecc559ca6bc18b8c4e2808bc78dbe769b0 upstream.
Drivers call netdev_set_num_tc() and then netdev_set_tc_queue() to set the queue count and offset for each TC. So the queue count and offset for the TCs may be zero for a short period after dev->num_tc has been set. If a TX packet is being transmitted at this time in the code path netdev_pick_tx() -> skb_tx_hash(), skb_tx_hash() may see nonzero dev->num_tc but zero qcount for the TC. The while loop that keeps looping while hash >= qcount will not end.
Fix it by checking the TC's qcount to be nonzero before using it.
Fixes: eadec877ce9c ("net: Add support for subordinate traffic classes to netdev_pick_tx") Reviewed-by: Andy Gospodarek gospo@broadcom.com Signed-off-by: Michael Chan michael.chan@broadcom.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- net/core/dev.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/net/core/dev.c b/net/core/dev.c index 5d9800804d4a4..6ed7810ed7bd4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2846,6 +2846,12 @@ static u16 skb_tx_hash(const struct net_device *dev,
qoffset = sb_dev->tc_to_txq[tc].offset; qcount = sb_dev->tc_to_txq[tc].count; + if (unlikely(!qcount)) { + net_warn_ratelimited("%s: invalid qcount, qoffset %u for tc %u\n", + sb_dev->name, qoffset, tc); + qoffset = 0; + qcount = dev->real_num_tx_queues; + } }
if (skb_rx_queue_recorded(skb)) {