3.16.50-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Florian Fainelli <[email protected]> commit b629be5c8399d7c423b92135eb43a86c924d1cbc upstream. There is a potential case where we might be failing to refill a control block, leaving it with both a NULL skb pointer *and* a NULL dma_unmap_addr. The way we process incoming packets, by first calling dma_unmap_single(), and then only checking for a potential NULL skb can lead to situations where do pass a NULL dma_unmap_addr() to dma_unmap_single(), resulting in an oops. Fix this my moving the NULL skb check earlier, since no backing skb also means no corresponding DMA mapping for this packet. Signed-off-by: Florian Fainelli <[email protected]> Signed-off-by: David S. Miller <[email protected]> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- drivers/net/ethernet/broadcom/genet/bcmgenet.c | 33 +++++++++++++++----------- 1 file changed, 19 insertions(+), 14 deletions(-) --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c @@ -1351,12 +1351,29 @@ static unsigned int bcmgenet_desc_rx(str while ((rxpktprocessed < rxpkttoprocess) && (rxpktprocessed < budget)) { + cb = &priv->rx_cbs[priv->rx_read_ptr]; + skb = cb->skb; + + rxpktprocessed++; + + priv->rx_read_ptr++; + priv->rx_read_ptr &= (priv->num_rx_bds - 1); + + /* We do not have a backing SKB, so we do not have a + * corresponding DMA mapping for this incoming packet since + * bcmgenet_rx_refill always either has both skb and mapping or + * none. + */ + if (unlikely(!skb)) { + dev->stats.rx_dropped++; + dev->stats.rx_errors++; + goto refill; + } + /* Unmap the packet contents such that we can use the * RSV from the 64 bytes descriptor when enabled and save * a 32-bits register read */ - cb = &priv->rx_cbs[priv->rx_read_ptr]; - skb = cb->skb; dma_unmap_single(kdev, dma_unmap_addr(cb, dma_addr), priv->rx_buf_len, DMA_FROM_DEVICE); @@ -1382,18 +1399,6 @@ static unsigned int bcmgenet_desc_rx(str __func__, p_index, priv->rx_c_index, priv->rx_read_ptr, dma_length_status); - rxpktprocessed++; - - priv->rx_read_ptr++; - priv->rx_read_ptr &= (priv->num_rx_bds - 1); - - /* out of memory, just drop packets at the hardware level */ - if (unlikely(!skb)) { - dev->stats.rx_dropped++; - dev->stats.rx_errors++; - goto refill; - } - if (unlikely(!(dma_flag & DMA_EOP) || !(dma_flag & DMA_SOP))) { netif_err(priv, rx_status, dev, "Droping fragmented packet!\n");
