[v2.6.34-stable 074/213] tg3: Avoid null pointer dereference in tg3_interrupt in netconsole mode

[Paul Gortmaker]

From: Nithin Nayak Sujir <nsujir@xxxxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 9c13cb8bb477a83b9a3c9e5a5478a4e21294a760 upstream.

When netconsole is enabled, logging messages generated during tg3_open
can result in a null pointer dereference for the uninitialized tg3
status block. Use the irq_sync flag to disable polling in the early
stages. irq_sync is cleared when the driver is enabling interrupts after
all initialization is completed.

Signed-off-by: Nithin Nayak Sujir <nsujir@xxxxxxxxxxxx>
Signed-off-by: Michael Chan <mchan@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[PG: drivers/net/ethernet/broadcom/tg3.c --> drivers/net/tg3.c in .34]
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 drivers/net/tg3.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index ecc41cffb470..e6045d1998af 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -5278,6 +5278,9 @@ static void tg3_poll_controller(struct net_device *dev)
 	int i;
 	struct tg3 *tp = netdev_priv(dev);
 
+	if (tg3_irq_sync(tp))
+		return;
+
 	for (i = 0; i < tp->irq_cnt; i++)
 		tg3_interrupt(tp->napi[i].irq_vec, &tp->napi[i]);
 }
@@ -14476,6 +14479,7 @@ static int __devinit tg3_init_one(struct pci_dev *pdev,
 	tp->pm_cap = pm_cap;
 	tp->rx_mode = TG3_DEF_RX_MODE;
 	tp->tx_mode = TG3_DEF_TX_MODE;
+	tp->irq_sync = 1;
 
 	if (tg3_debug > 0)
 		tp->msg_enable = tg3_debug;
-- 
1.8.5.2

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