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Commit dea39aca authored by Stefan Wahren's avatar Stefan Wahren Committed by David S. Miller
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net: lan78xx: Fix race in tx pending skb size calculation 

The skb size calculation in lan78xx_tx_bh is in race with the start_xmit,
which could lead to rare kernel oopses. So protect the whole skb walk with
a spin lock. As a benefit we can unlink the skb directly.

This patch was tested on Raspberry Pi 3B+

Link: https://github.com/raspberrypi/linux/issues/2608


Fixes: 55d7de9d ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarFloris Bos <bos@je-eigen-domein.nl>
Signed-off-by: default avatarStefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b5d2d75e

drivers/net/usb/lan78xx.c

+4 −1
Original line number Diff line number Diff line
@@ -3344,6 +3344,7 @@ static void lan78xx_tx_bh(struct lan78xx_net *dev) 
	pkt_cnt = 0;

	count = 0;

	length = 0;

	spin_lock_irqsave(&tqp->lock, flags);

	for (skb = tqp->next; pkt_cnt < tqp->qlen; skb = skb->next) {

		if (skb_is_gso(skb)) {

			if (pkt_cnt) {
@@ -3352,7 +3353,8 @@ static void lan78xx_tx_bh(struct lan78xx_net *dev) 
			}

			count = 1;

			length = skb->len - TX_OVERHEAD;

			skb2 = skb_dequeue(tqp);

			__skb_unlink(skb, tqp);

			spin_unlock_irqrestore(&tqp->lock, flags);

			goto gso_skb;

		}
@@ -3361,6 +3363,7 @@ static void lan78xx_tx_bh(struct lan78xx_net *dev) 
		skb_totallen = skb->len + roundup(skb_totallen, sizeof(u32));

		pkt_cnt++;

	}

	spin_unlock_irqrestore(&tqp->lock, flags);



	/* copy to a single skb */

	skb = alloc_skb(skb_totallen, GFP_ATOMIC);