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p54: avoid accessing the data mapped to streaming DMA 

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
zero-sugar-mainline-defconfig
Jia-Ju Bai 2020-08-02 21:29:49 +08:00 committed by Kalle Valo
parent e9cf68ff4e
commit 478762855b
1 changed files with 3 additions and 1 deletions
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4
drivers/net/wireless/intersil/p54/p54pci.c
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@ -333,10 +333,12 @@ static void p54p_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
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 = dma_map_single(&priv->pdev->dev, skb->data, skb->len,
DMA_TO_DEVICE);
@ -350,7 +352,7 @@ static void p54p_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
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;