From 478762855b5ae9f68fa6ead1edf7abada70fcd5f Mon Sep 17 00:00:00 2001 From: Jia-Ju Bai Date: Sun, 2 Aug 2020 21:29:49 +0800 Subject: [PATCH] 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: Signed-off-by: Jia-Ju Bai Acked-by: Christian Lamparter Signed-off-by: Kalle Valo Link: https://lore.kernel.org/r/20200802132949.26788-1-baijiaju@tsinghua.edu.cn --- drivers/net/wireless/intersil/p54/p54pci.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/intersil/p54/p54pci.c b/drivers/net/wireless/intersil/p54/p54pci.c index 94064d7cff52..e97ee547b9f3 100644 --- a/drivers/net/wireless/intersil/p54/p54pci.c +++ b/drivers/net/wireless/intersil/p54/p54pci.c @@ -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;