From 478762855b5ae9f68fa6ead1edf7abada70fcd5f Mon Sep 17 00:00:00 2001

From: Jia-Ju Bai <baijiaju@tsinghua.edu.cn>

Date: Sun, 2 Aug 2020 21:29:49 +0800

Subject: [PATCH] p54: avoid accessing the data mapped to streaming DMA

Git-commit: 478762855b5ae9f68fa6ead1edf7abada70fcd5f

Patch-mainline: v5.10-rc1

References: git-fixes

In p54p_tx(), skb->data is mapped to streaming DMA on line 337:

  mapping = pci_map_single(..., skb->data, ...);

Then skb->data is accessed on line 349:

  desc->device_addr = ((struct p54_hdr *)skb->data)->req_id;

This access may cause data inconsistency between CPU cache and hardware.

To fix this problem, ((struct p54_hdr *)skb->data)->req_id is stored in

a local variable before DMA mapping, and then the driver accesses this

local variable instead of skb->data.

Cc: <stable@vger.kernel.org>

Signed-off-by: Jia-Ju Bai <baijiaju@tsinghua.edu.cn>

Acked-by: Christian Lamparter <chunkeey@gmail.com>

Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

Link: https://lore.kernel.org/r/20200802132949.26788-1-baijiaju@tsinghua.edu.cn

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/net/wireless/intersil/p54/p54pci.c |    4 +++-

 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/net/wireless/intersil/p54/p54pci.c

+++ b/drivers/net/wireless/intersil/p54/p54pci.c

@@ -332,10 +332,12 @@ static void p54p_tx(struct ieee80211_hw

 	struct p54p_desc *desc;

 	dma_addr_t mapping;

 	u32 idx, i;

+	__le32 device_addr;

 	spin_lock_irqsave(&priv->lock, flags);

 	idx = le32_to_cpu(ring_control->host_idx[1]);

 	i = idx % ARRAY_SIZE(ring_control->tx_data);

+	device_addr = ((struct p54_hdr *)skb->data)->req_id;

 	mapping = pci_map_single(priv->pdev, skb->data, skb->len,

 				 PCI_DMA_TODEVICE);

@@ -349,7 +351,7 @@ static void p54p_tx(struct ieee80211_hw

 	desc = &ring_control->tx_data[i];

 	desc->host_addr = cpu_to_le32(mapping);

-	desc->device_addr = ((struct p54_hdr *)skb->data)->req_id;

+	desc->device_addr = device_addr;

 	desc->len = cpu_to_le16(skb->len);

 	desc->flags = 0;