Commit 8b2c13b2 authored by Jia-Ju Bai's avatar Jia-Ju Bai Committed by Kalle Valo
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rtlwifi: rtl8723ae: avoid accessing the data mapped to streaming DMA 



In rtl8723e_tx_fill_cmddesc(), skb->data is mapped to streaming DMA on
line 531:
  dma_addr_t mapping = dma_map_single(..., skb->data, ...);

On line 534, skb->data is assigned to hdr after cast:
  struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)(skb->data);

Then hdr->frame_control is accessed on line 535:
  __le16 fc = hdr->frame_control;

This DMA access may cause data inconsistency between CPU and hardwre.

To fix this bug, hdr->frame_control is accessed before the DMA mapping.

Signed-off-by: default avatarJia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: default avatarKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201119015218.12220-1-baijiaju1990@gmail.com
parent ff765483

drivers/net/wireless/realtek/rtlwifi/rtl8723ae/trx.c

+3 −3
Original line number Diff line number Diff line
@@ -528,12 +528,12 @@ void rtl8723e_tx_fill_cmddesc(struct ieee80211_hw *hw, 
	u8 fw_queue = QSLT_BEACON;

	__le32 *pdesc = (__le32 *)pdesc8;



	dma_addr_t mapping = dma_map_single(&rtlpci->pdev->dev, skb->data,

					    skb->len, DMA_TO_DEVICE);



	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)(skb->data);

	__le16 fc = hdr->frame_control;



	dma_addr_t mapping = dma_map_single(&rtlpci->pdev->dev, skb->data,

					    skb->len, DMA_TO_DEVICE);



	if (dma_mapping_error(&rtlpci->pdev->dev, mapping)) {

		rtl_dbg(rtlpriv, COMP_SEND, DBG_TRACE,

			"DMA mapping error\n");