From: Colin Ian King <colin.king@canonical.com>
Date: Thu, 4 Oct 2018 18:57:32 +0100
Subject: ixgbe: don't clear_bit on xdp_ring->state if xdp_ring is null
Patch-mainline: v5.0-rc1
Git-commit: 0db4a47c05e6b5f7dda2a5d8b213ade5373afa49
References: bsc#1113994 FATE#326315 FATE#326317

There is an earlier check to see if xdp_ring is null when configuring
the tx ring, so assuming that it can still be null, the clearing of
the xdp_ring->state currently could end up with a null pointer
dereference.  Fix this by only clearing the bit if xdp_ring is not null.

Detected by CoverityScan, CID#1473795 ("Dereference after null check")

Fixes: 024aa5800f32 ("ixgbe: added Rx/Tx ring disable/enable functions")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -10541,7 +10541,8 @@ void ixgbe_txrx_ring_enable(struct ixgbe
 	ixgbe_configure_rx_ring(adapter, rx_ring);
 
 	clear_bit(__IXGBE_TX_DISABLED, &tx_ring->state);
-	clear_bit(__IXGBE_TX_DISABLED, &xdp_ring->state);
+	if (xdp_ring)
+		clear_bit(__IXGBE_TX_DISABLED, &xdp_ring->state);
 }
 
 /**