gve: fix the wrong AdminQ buffer overflow check

The 'tail' pointer is also free-running count, so it needs to be masked
as 'adminq_prod_cnt' does, to become an index value of AdminQ buffer.

Fixes: 5cdad90de62c ("gve: Batch AQ commands for creating and destroying queues.")
Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Reviewed-by: Catherine Sullivan <csully@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c b/drivers/net/ethernet/google/gve/gve_adminq.c
index 5bb56b4..f089d33 100644 (file)
--- a/drivers/net/ethernet/google/gve/gve_adminq.c
+++ b/drivers/net/ethernet/google/gve/gve_adminq.c
@@ -322,7 +322,8 @@ static int gve_adminq_issue_cmd(struct gve_priv *priv,
        tail = ioread32be(&priv->reg_bar0->adminq_event_counter);
 
        // Check if next command will overflow the buffer.
-       if (((priv->adminq_prod_cnt + 1) & priv->adminq_mask) == tail) {
+       if (((priv->adminq_prod_cnt + 1) & priv->adminq_mask) ==
+           (tail & priv->adminq_mask)) {
                int err;
 
                // Flush existing commands to make room.
@@ -332,7 +333,8 @@ static int gve_adminq_issue_cmd(struct gve_priv *priv,
 
                // Retry.
                tail = ioread32be(&priv->reg_bar0->adminq_event_counter);
-               if (((priv->adminq_prod_cnt + 1) & priv->adminq_mask) == tail) {
+               if (((priv->adminq_prod_cnt + 1) & priv->adminq_mask) ==
+                   (tail & priv->adminq_mask)) {
                        // This should never happen. We just flushed the
                        // command queue so there should be enough space.
                        return -ENOMEM;