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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Alexander Duyck <alexander.h.duyck@intel.com>,
        Andrew Bowers <andrewx.bowers@intel.com>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 070/241] i40e/i40evf: Fix use after free in Rx cleanup path
Date:   Mon, 19 Mar 2018 19:05:35 +0100
Message-Id: <20180319180754.100136355@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexander Duyck <alexander.h.duyck@intel.com>


[ Upstream commit 741b8b832a57402380be79d7d11a59eaf57fff3b ]

We need to reset skb back to NULL when we have freed it in the Rx cleanup
path.  I found one spot where this wasn't occurring so this patch fixes it.

Change-ID: Iaca68934200732cd4a63eb0bd83b539c95f8c4dd
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/intel/i40e/i40e_txrx.c   |    1 +
 drivers/net/ethernet/intel/i40evf/i40e_txrx.c |    1 +
 2 files changed, 2 insertions(+)

--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -1820,6 +1820,7 @@ static int i40e_clean_rx_irq(struct i40e
 		 */
 		if (unlikely(i40e_test_staterr(rx_desc, BIT(I40E_RXD_QW1_ERROR_SHIFT)))) {
 			dev_kfree_skb_any(skb);
+			skb = NULL;
 			continue;
 		}
 
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
@@ -1262,6 +1262,7 @@ static int i40e_clean_rx_irq(struct i40e
 		 */
 		if (unlikely(i40e_test_staterr(rx_desc, BIT(I40E_RXD_QW1_ERROR_SHIFT)))) {
 			dev_kfree_skb_any(skb);
+			skb = NULL;
 			continue;
 		}