From: Jia-Ju Bai <baiji...@tsinghua.edu.cn> 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: <sta...@vger.kernel.org> Signed-off-by: Jia-Ju Bai <baiji...@tsinghua.edu.cn> Acked-by: Christian Lamparter <chunk...@gmail.com> Signed-off-by: Kalle Valo <kv...@codeaurora.org> Link: https://lore.kernel.org/r/20200802132949.26788-1-baiji...@tsinghua.edu.cn Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/net/wireless/intersil/p54/p54pci.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/net/wireless/intersil/p54/p54pci.c +++ b/drivers/net/wireless/intersil/p54/p54pci.c @@ -329,10 +329,12 @@ static void p54p_tx(struct ieee80211_hw 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); @@ -346,7 +348,7 @@ static void p54p_tx(struct ieee80211_hw 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;
