linux-kernel - [PATCH] e1000: ethtool: check on netif_running() before calling e1000

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Date:   Wed, 18 Jul 2018 12:18:51 -0700
From:   Bo Chen <chenbo@....edu>
To:     jeffrey.t.kirsher@...el.com
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, phenix1108@...il.com,
        Bo Chen <chenbo@....edu>
Subject: [PATCH] e1000: ethtool: check on netif_running() before calling e1000_up()

When the device is not up, the call to 'e1000_up()' from the error handling path
of 'e1000_set_ringparam()' causes a kernel oops with a null-pointer
dereference. The null-pointer dereference is triggered in function
'e1000_alloc_rx_buffers()' at line 'buffer_info = &rx_ring->buffer_info[i]'.

This bug was reported by COD, a tool for testing kernel module binaries I am
building. This bug was also detected by KFI from Dr. Kai Cong.

This patch fixes the bug by checking on 'netif_running()' before calling
'e1000_up()' in 'e1000_set_ringparam()'.

Signed-off-by: Bo Chen <chenbo@....edu>
---
 drivers/net/ethernet/intel/e1000/e1000_ethtool.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
index bdb3f8e65ed4..c1e4e94f100f 100644
--- a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
+++ b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
@@ -644,7 +644,8 @@ static int e1000_set_ringparam(struct net_device *netdev,
 err_alloc_rx:
 	kfree(txdr);
 err_alloc_tx:
-	e1000_up(adapter);
+	if (netif_running(adapter->netdev))
+		e1000_up(adapter);
 err_setup:
 	clear_bit(__E1000_RESETTING, &adapter->flags);
 	return err;
-- 
2.17.0