From ff76548338947c2c45b7aaf1d182e331398279b7 Mon Sep 17 00:00:00 2001 From: Jia-Ju Bai Date: Thu, 19 Nov 2020 09:52:05 +0800 Subject: [PATCH] rtlwifi: rtl8192de: avoid accessing the data mapped to streaming DMA In rtl92de_tx_fill_cmddesc(), skb->data is mapped to streaming DMA on line 667: dma_addr_t mapping = dma_map_single(..., skb->data, ...); On line 669, 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 670: __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: Jia-Ju Bai Signed-off-by: Kalle Valo Link: https://lore.kernel.org/r/20201119015205.12162-1-baijiaju1990@gmail.com --- drivers/net/wireless/realtek/rtlwifi/rtl8192de/trx.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8192de/trx.c b/drivers/net/wireless/realtek/rtlwifi/rtl8192de/trx.c index 8944712274b5..c02813fba934 100644 --- a/drivers/net/wireless/realtek/rtlwifi/rtl8192de/trx.c +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192de/trx.c @@ -664,12 +664,14 @@ void rtl92de_tx_fill_cmddesc(struct ieee80211_hw *hw, struct rtl_ps_ctl *ppsc = rtl_psc(rtlpriv); struct rtl_hal *rtlhal = rtl_hal(rtlpriv); u8 fw_queue = QSLT_BEACON; - 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; __le32 *pdesc = (__le32 *)pdesc8; + 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"); -- 2.11.0