net: mvneta: fix refilling for Rx DMA buffers

With the actual code, if a memory allocation error happens while
refilling a Rx descriptor, then the original Rx buffer is both passed
to the networking stack (in a SKB) and let in the Rx ring. This leads
to various kernel oops and crashes.

As a fix, this patch moves Rx descriptor refilling ahead of building
SKB with the associated Rx buffer. In case of a memory allocation
failure, data is dropped and the original DMA buffer is put back into
the Rx ring.

Signed-off-by: Simon Guinot <simon.guinot@sequanux.org>
Fixes: c5aff18204da ("net: mvneta: driver for Marvell Armada 370/XP network unit")
Cc: <stable@vger.kernel.org> # v3.8+
Tested-by: Yoann Sculo <yoann@sculo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 370e20ed224c5c76eaca92954be5800d09d81ada..62e48bc0cb23ba98ed2cb2c447af288bd1c3906d 100644 (file)
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -1462,7 +1462,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
                     struct mvneta_rx_queue *rxq)
 {
        struct net_device *dev = pp->dev;
-       int rx_done, rx_filled;
+       int rx_done;
        u32 rcvd_pkts = 0;
        u32 rcvd_bytes = 0;
 
@@ -1473,7 +1473,6 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
                rx_todo = rx_done;
 
        rx_done = 0;
-       rx_filled = 0;
 
        /* Fairness NAPI loop */
        while (rx_done < rx_todo) {
@@ -1484,7 +1483,6 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
                int rx_bytes, err;
 
                rx_done++;
-               rx_filled++;
                rx_status = rx_desc->status;
                rx_bytes = rx_desc->data_size - (ETH_FCS_LEN + MVNETA_MH_SIZE);
                data = (unsigned char *)rx_desc->buf_cookie;
@@ -1524,6 +1522,14 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
                        continue;
                }
 
+               /* Refill processing */
+               err = mvneta_rx_refill(pp, rx_desc);
+               if (err) {
+                       netdev_err(dev, "Linux processing - Can't refill\n");
+                       rxq->missed++;
+                       goto err_drop_frame;
+               }
+
                skb = build_skb(data, pp->frag_size > PAGE_SIZE ? 0 : pp->frag_size);
                if (!skb)
                        goto err_drop_frame;
@@ -1543,14 +1549,6 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
                mvneta_rx_csum(pp, rx_status, skb);
 
                napi_gro_receive(&pp->napi, skb);
-
-               /* Refill processing */
-               err = mvneta_rx_refill(pp, rx_desc);
-               if (err) {
-                       netdev_err(dev, "Linux processing - Can't refill\n");
-                       rxq->missed++;
-                       rx_filled--;
-               }
        }
 
        if (rcvd_pkts) {
@@ -1563,7 +1561,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
        }
 
        /* Update rxq management counters */
-       mvneta_rxq_desc_num_update(pp, rxq, rx_done, rx_filled);
+       mvneta_rxq_desc_num_update(pp, rxq, rx_done, rx_done);
 
        return rx_done;
 }