netdev - [PATCH][-next] ixgbe: don't clear_bit on xdp_ring->state if xdp

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Message-Id: <20181004175732.28329-1-colin.king@canonical.com>
Date:   Thu,  4 Oct 2018 18:57:32 +0100
From:   Colin King <colin.king@...onical.com>
To:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        "David S . Miller" <davem@...emloft.net>,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org
Subject: [PATCH][-next] 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>
---
 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 0049a2becd7e..8e4756247324 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);
 }
 
 /**
-- 
2.17.1