Commit d89a2adb authored May 03, 2018 by Michael Chan Committed by David S. Miller May 04, 2018

tg3: Fix vunmap() BUG_ON() triggered from tg3_free_consistent().



tg3_free_consistent() calls dma_free_coherent() to free tp->hw_stats
under spinlock and can trigger BUG_ON() in vunmap() because vunmap()
may sleep.  Fix it by removing the spinlock and relying on the
TG3_FLAG_INIT_COMPLETE flag to prevent race conditions between
tg3_get_stats64() and tg3_free_consistent().  TG3_FLAG_INIT_COMPLETE
is always cleared under tp->lock before tg3_free_consistent()
and therefore tg3_get_stats64() can safely access tp->hw_stats
under tp->lock if TG3_FLAG_INIT_COMPLETE is set.

Fixes: f5992b72 ("tg3: Fix race condition in tg3_get_stats64().")
Reported-by: Zumeng Chen <zumeng.chen@gmail.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent af50e4ba

drivers/net/ethernet/broadcom/tg3.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -8733,14 +8733,15 @@ 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);
		/* tp->hw_stats can be referenced safely:
		* 1. under rtnl_lock
		* 2. or under tp->lock if TG3_FLAG_INIT_COMPLETE is set.
		*/
		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);
		}

		/*
		@@ -14178,7 +14179,7 @@ static void tg3_get_stats64(struct net_device *dev,
		struct tg3 *tp = netdev_priv(dev);

		spin_lock_bh(&tp->lock);
		if (!tp->hw_stats) {
		if (!tp->hw_stats \|\| !tg3_flag(tp, INIT_COMPLETE)) {
		*stats = tp->net_stats_prev;
		spin_unlock_bh(&tp->lock);
		return;