[PATCH net] tg3: Fix race condition in tg3_get_stats64().

[Michael Chan]

The driver's ndo_get_stats64() method is not always called under RTNL.
So it can race with driver close or ethtool reconfigurations.  Fix the
race condition by taking tp->lock spinlock in tg3_free_consistent()
when freeing the tp->hw_stats memory block.  tg3_get_stats64() is
already taking tp->lock.

Reported-by: Wang Yufen <wangyu...@huawei.com>
Signed-off-by: Michael Chan <michael.c...@broadcom.com>
---
 drivers/net/ethernet/broadcom/tg3.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/tg3.c 
b/drivers/net/ethernet/broadcom/tg3.c
index 185e9e0..ae42de4 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -8720,11 +8720,14 @@ static void tg3_free_consistent(struct tg3 *tp)
        tg3_mem_rx_release(tp);
        tg3_mem_tx_release(tp);
 
+       /* Protect tg3_get_stats64() from reading freed tp->hw_stats. */
+       tg3_full_lock(tp, 0);
        if (tp->hw_stats) {
                dma_free_coherent(&tp->pdev->dev, sizeof(struct tg3_hw_stats),
                                  tp->hw_stats, tp->stats_mapping);
                tp->hw_stats = NULL;
        }
+       tg3_full_unlock(tp);
 }
 
 /*
-- 
1.8.3.1