staging: fsl-dpaa2/eth: Fix incorrect kfree

Use netdev_alloc_frag() instead of kmalloc to allocate space for
the S/G table of egress multi-buffer frames.

This fixes a bug where an unaligned pointer received from the
allocator would be overwritten with the 64B aligned value,
leading to a wrong address being later passed to kfree.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c

@@ -374,12 +374,14 @@ static int build_sg_fd(struct dpaa2_eth_priv *priv,
 	/* Prepare the HW SGT structure */
 	sgt_buf_size = priv->tx_data_offset +
 		       sizeof(struct dpaa2_sg_entry) * (1 + num_dma_bufs);
-	sgt_buf = kzalloc(sgt_buf_size + DPAA2_ETH_TX_BUF_ALIGN, GFP_ATOMIC);
+	sgt_buf = netdev_alloc_frag(sgt_buf_size + DPAA2_ETH_TX_BUF_ALIGN);
 	if (unlikely(!sgt_buf)) {
 		err = -ENOMEM;
 		goto sgt_buf_alloc_failed;
 	}
 	sgt_buf = PTR_ALIGN(sgt_buf, DPAA2_ETH_TX_BUF_ALIGN);
+	memset(sgt_buf, 0, sgt_buf_size);
+
 	sgt = (struct dpaa2_sg_entry *)(sgt_buf + priv->tx_data_offset);
 
 	/* Fill in the HW SGT structure.
@@ -421,7 +423,7 @@ static int build_sg_fd(struct dpaa2_eth_priv *priv,
 	return 0;
 
 dma_map_single_failed:
-	kfree(sgt_buf);
+	skb_free_frag(sgt_buf);
 sgt_buf_alloc_failed:
 	dma_unmap_sg(dev, scl, num_sg, DMA_BIDIRECTIONAL);
 dma_map_sg_failed:
@@ -525,9 +527,9 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
 		return;
 	}
 
-	/* Free SGT buffer kmalloc'ed on tx */
+	/* Free SGT buffer allocated on tx */
 	if (fd_format != dpaa2_fd_single)
-		kfree(skbh);
+		skb_free_frag(skbh);
 
 	/* Move on with skb release */
 	dev_kfree_skb(skb);