The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From dea39aca1d7aef1e2b95b07edeacf04cc8863a2e Mon Sep 17 00:00:00 2001

From: Stefan Wahren stefan.wahren@i2se.com Date: Sun, 15 Jul 2018 21:53:20 +0200 Subject: [PATCH] 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: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet") Cc: stable stable@vger.kernel.org Signed-off-by: Floris Bos bos@je-eigen-domein.nl Signed-off-by: Stefan Wahren stefan.wahren@i2se.com Signed-off-by: David S. Miller davem@davemloft.net

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c index 2e4130746c40..ed10d49eb5e0 100644 --- a/drivers/net/usb/lan78xx.c +++ b/drivers/net/usb/lan78xx.c @@ -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);