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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,
        Thomas Falcon <tlfalcon@linux.vnet.ibm.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.14 107/496] ibmvnic: Check for NULL skbs in NAPI poll routine
Date:   Mon, 28 May 2018 11:58:12 +0200
Message-Id: <20180528100324.412139231@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>

[ Upstream commit abe27a885d9e6575e663a16176dabc58ce9d7188 ]

After introduction of commit d0869c0071e4, there were some instances of
RX queue entries from a previous session (before the device was closed
and reopened) returned to the NAPI polling routine. Since the corresponding
socket buffers were freed, this resulted in a panic on reopen. Include
a check for a NULL skb here to avoid this.

Fixes: d0869c0071e4 ("ibmvnic: Clean RX pool buffers during device close")
Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/ibm/ibmvnic.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -1668,6 +1668,11 @@ restart_poll:
 			dev_kfree_skb_any(rx_buff->skb);
 			remove_buff_from_pool(adapter, rx_buff);
 			continue;
+		} else if (!rx_buff->skb) {
+			/* free the entry */
+			next->rx_comp.first = 0;
+			remove_buff_from_pool(adapter, rx_buff);
+			continue;
 		}
 
 		length = be32_to_cpu(next->rx_comp.len);