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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
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1 changed files with 3 additions and 1 deletions
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@ -333,10 +333,12 @@ static void p54p_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
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struct p54p_desc *desc;
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dma_addr_t mapping;
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u32 idx, i;
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__le32 device_addr;
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spin_lock_irqsave(&priv->lock, flags);
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idx = le32_to_cpu(ring_control->host_idx[1]);
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i = idx % ARRAY_SIZE(ring_control->tx_data);
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device_addr = ((struct p54_hdr *)skb->data)->req_id;
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mapping = dma_map_single(&priv->pdev->dev, skb->data, skb->len,
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DMA_TO_DEVICE);
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@ -350,7 +352,7 @@ static void p54p_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
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desc = &ring_control->tx_data[i];
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desc->host_addr = cpu_to_le32(mapping);
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desc->device_addr = ((struct p54_hdr *)skb->data)->req_id;
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desc->device_addr = device_addr;
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desc->len = cpu_to_le16(skb->len);
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desc->flags = 0;
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