e1000e: prevent null ptr dereference in e1000_tx_queue()

tx_desc can be dereferenced as a null pointer when count is passed in
as 0.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index 393b76d27536..4bf843ac7ea3 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -4629,7 +4629,7 @@ static void e1000_tx_queue(struct e1000_adapter *adapter,
 
         i = tx_ring->next_to_use;
 
-        while (count--) {
+        do {
                 buffer_info = &tx_ring->buffer_info[i];
                 tx_desc = E1000_TX_DESC(*tx_ring, i);
                 tx_desc->buffer_addr = cpu_to_le64(buffer_info->dma);
@@ -4640,7 +4640,7 @@ static void e1000_tx_queue(struct e1000_adapter *adapter,
                 i++;
                 if (i == tx_ring->count)
                         i = 0;
-        }
+        } while (--count > 0);
 
         tx_desc->lower.data |= cpu_to_le32(adapter->txd_cmd);