tg3: avoid double-freeing of rx data memory

If build_skb fails the memory associated with the ring buffer is freed but
the ri->data member is not zeroed in this case. This causes a double-free
of this memory in tg3_free_rings->... path. The patch moves this block after
setting ri->data to NULL.
It would be nice to fix this bug also in stable >= v3.4 trees.

Cc: Nithin Nayak Sujir <nsujir@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Acked-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 819d87c..00c5be8 100644 (file)
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -6862,12 +6862,6 @@ static int tg3_rx(struct tg3_napi *tnapi, int budget)
                        pci_unmap_single(tp->pdev, dma_addr, skb_size,
                                         PCI_DMA_FROMDEVICE);
 
-                       skb = build_skb(data, frag_size);
-                       if (!skb) {
-                               tg3_frag_free(frag_size != 0, data);
-                               goto drop_it_no_recycle;
-                       }
-                       skb_reserve(skb, TG3_RX_OFFSET(tp));
                        /* Ensure that the update to the data happens
                         * after the usage of the old DMA mapping.
                         */
@@ -6875,6 +6869,12 @@ static int tg3_rx(struct tg3_napi *tnapi, int budget)
 
                        ri->data = NULL;
 
+                       skb = build_skb(data, frag_size);
+                       if (!skb) {
+                               tg3_frag_free(frag_size != 0, data);
+                               goto drop_it_no_recycle;
+                       }
+                       skb_reserve(skb, TG3_RX_OFFSET(tp));
                } else {
                        tg3_recycle_rx(tnapi, tpr, opaque_key,
                                       desc_idx, *post_ptr);