From: Jia-Ju Bai baijiaju@tsinghua.edu.cn
stable inclusion from linux-4.19.155 commit df605e1b5c2ccb55e42c144aecca4bbd76ff149f
--------------------------------
commit 478762855b5ae9f68fa6ead1edf7abada70fcd5f upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- 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 57ad56435dda..8bc0286b4f8c 100644 --- a/drivers/net/wireless/intersil/p54/p54pci.c +++ b/drivers/net/wireless/intersil/p54/p54pci.c @@ -332,10 +332,12 @@ 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 = pci_map_single(priv->pdev, skb->data, skb->len, PCI_DMA_TODEVICE); @@ -349,7 +351,7 @@ 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;