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 0c5661ecc5dd7ce296870a3eb7b62b1b280a5e89 Mon Sep 17 00:00:00 2001

From: Emil Tantilov emil.s.tantilov@intel.com Date: Fri, 23 Feb 2018 12:39:41 -0800 Subject: [PATCH] ixgbe: fix crash in build_skb Rx code path

Add check for build_skb enabled ring in ixgbe_dma_sync_frag(). In that case &skb_shinfo(skb)->frags[0] may not always be set which can lead to a crash. Instead we derive the page offset from skb->data.

Fixes: 42073d91a214 ("ixgbe: Have the CPU take ownership of the buffers sooner") CC: stable stable@vger.kernel.org Reported-by: Ambarish Soman asoman@redhat.com Suggested-by: Alexander Duyck alexander.h.duyck@intel.com Signed-off-by: Emil Tantilov emil.s.tantilov@intel.com Tested-by: Andrew Bowers andrewx.bowers@intel.com Signed-off-by: Jeff Kirsher jeffrey.t.kirsher@intel.com Signed-off-by: David S. Miller davem@davemloft.net

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c index 0da5aa2c8aba..9fc063af233c 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -1888,6 +1888,14 @@ static void ixgbe_dma_sync_frag(struct ixgbe_ring *rx_ring, ixgbe_rx_pg_size(rx_ring), DMA_FROM_DEVICE, IXGBE_RX_DMA_ATTR); + } else if (ring_uses_build_skb(rx_ring)) { + unsigned long offset = (unsigned long)(skb->data) & ~PAGE_MASK; + + dma_sync_single_range_for_cpu(rx_ring->dev, + IXGBE_CB(skb)->dma, + offset, + skb_headlen(skb), + DMA_FROM_DEVICE); } else { struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];