[PATCH net v1] net: stmmac: TSO: Fix unaligned DMA unmap for non-paged SKB data

[Furong Xu <0x1207@gmail.com>]

Commit 66600fac7a98 ("net: stmmac: TSO: Fix unbalanced DMA map/unmap for
non-paged SKB data") assigns a wrong DMA buffer address that is added an
offset of proto_hdr_len to tx_q->tx_skbuff_dma[entry].buf on a certain
platform that the DMA AXI address width is configured to 40-bit/48-bit,
stmmac_tx_clean() will try to unmap this illegal DMA buffer address
and many crashes are reported: [1] [2].

This patch guarantees that DMA address is passed to stmmac_tx_clean()
unmodified and without offset.

[1] https://lore.kernel.org/all/d8112193-0386-4e14-b516-37c2d838171a@nvidia.com/
[2] https://lore.kernel.org/all/klkzp5yn5kq5efgtrow6wbvnc46bcqfxs65nz3qy77ujr5turc@bwwhelz2l4dw/

Reported-by: Jon Hunter <jonathanh@nvidia.com>
Reported-by: Thierry Reding <thierry.reding@gmail.com>
Suggested-by: Russell King (Oracle) <linux@armlinux.org.uk>
Fixes: 66600fac7a98 ("net: stmmac: TSO: Fix unbalanced DMA map/unmap for non-paged SKB data")
Signed-off-by: Furong Xu <0x1207@gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 9b262cdad60b..7227f8428b5e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4192,8 +4192,8 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct stmmac_txq_stats *txq_stats;
 	struct stmmac_tx_queue *tx_q;
 	u32 pay_len, mss, queue;
+	dma_addr_t tso_hdr, des;
 	u8 proto_hdr_len, hdr;
-	dma_addr_t des;
 	bool set_ic;
 	int i;
 
@@ -4279,6 +4279,7 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
 			     DMA_TO_DEVICE);
 	if (dma_mapping_error(priv->device, des))
 		goto dma_map_err;
+	tso_hdr = des;
 
 	if (priv->dma_cap.addr64 <= 32) {
 		first->des0 = cpu_to_le32(des);
@@ -4310,7 +4311,7 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * this DMA buffer right after the DMA engine completely finishes the
 	 * full buffer transmission.
 	 */
-	tx_q->tx_skbuff_dma[tx_q->cur_tx].buf = des;
+	tx_q->tx_skbuff_dma[tx_q->cur_tx].buf = tso_hdr;
 	tx_q->tx_skbuff_dma[tx_q->cur_tx].len = skb_headlen(skb);
 	tx_q->tx_skbuff_dma[tx_q->cur_tx].map_as_page = false;
 	tx_q->tx_skbuff_dma[tx_q->cur_tx].buf_type = STMMAC_TXBUF_T_SKB;
-- 
2.34.1