netdev - [net-next 02/12] ixgbe: don't clear_bit on xdp_ring->state if xdp

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Date:   Wed,  7 Nov 2018 14:48:20 -0800
From:   Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:     davem@...emloft.net
Cc:     Colin Ian King <colin.king@...onical.com>, netdev@...r.kernel.org,
        nhorman@...hat.com, sassmann@...hat.com,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-next 02/12] ixgbe: don't clear_bit on xdp_ring->state if xdp_ring is null

From: Colin Ian King <colin.king@...onical.com>

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@...onical.com>
Tested-by: Andrew Bowers <andrewx.bowers@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 113b38e0defb..aeda1834e66a 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -10517,7 +10517,8 @@ void ixgbe_txrx_ring_enable(struct ixgbe_adapter *adapter, int ring)
 	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);
 }
 
 /**
-- 
2.19.1