From: Jia-Ju Bai <baijiaju@tsinghua.edu.cn>
To: chunkeey@googlemail.com, kvalo@codeaurora.org,
davem@davemloft.net, kuba@kernel.org
Cc: linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
Jia-Ju Bai <baijiaju@tsinghua.edu.cn>
Subject: [PATCH] p54: avoid accessing the data mapped to streaming DMA
Date: Sun, 2 Aug 2020 21:29:49 +0800 [thread overview]
Message-ID: <20200802132949.26788-1-baijiaju@tsinghua.edu.cn> (raw)
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.
Signed-off-by: Jia-Ju Bai <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 80ad0b7eaef4..f8c6027cab6b 100644
--- 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 *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);
@@ -346,7 +348,7 @@ 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;
--
2.17.1
next reply other threads:[~2020-08-02 13:37 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-02 13:29 Jia-Ju Bai [this message]
2020-08-18 12:41 ` [PATCH] p54: avoid accessing the data mapped to streaming DMA Kalle Valo
2020-08-18 17:27 ` Christian Lamparter
2020-08-26 16:02 ` Kalle Valo
2020-08-28 21:19 ` Christian Lamparter
2020-08-31 14:00 ` Kalle Valo
2020-09-01 9:34 ` Kalle Valo
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