2020-11-19 01:53:55

by Jia-Ju Bai

Subject: [PATCH v2 1/4 resend] rtlwifi: rtl8188ee: avoid accessing the data mapped to streaming DMA

In rtl88ee_tx_fill_cmddesc(), skb->data is mapped to streaming DMA on
line 677:
dma_addr_t mapping = dma_map_single(..., skb->data, ...);

On line 680, 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 681:
__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 <[email protected]>
---
v2:
* Use "rtlwifi" as subject prefix and have all rtlwifi patches in the
same pathset.
Thank Ping and Larry for good advice.

---
drivers/net/wireless/realtek/rtlwifi/rtl8188ee/trx.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8188ee/trx.c b/drivers/net/wireless/realtek/rtlwifi/rtl8188ee/trx.c
index b9775eec4c54..c948dafa0c80 100644
--- a/drivers/net/wireless/realtek/rtlwifi/rtl8188ee/trx.c
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8188ee/trx.c
@@ -674,12 +674,12 @@ void rtl88ee_tx_fill_cmddesc(struct ieee80211_hw *hw,
u8 fw_queue = QSLT_BEACON;
__le32 *pdesc = (__le32 *)pdesc8;

- 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;

+ 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");
--
2.17.1

2020-11-24 15:09:26

by Kalle Valo

Subject: Re: [PATCH v2 1/4 resend] rtlwifi: rtl8188ee: avoid accessing the data mapped to streaming DMA

Jia-Ju Bai <[email protected]> wrote:

> In rtl88ee_tx_fill_cmddesc(), skb->data is mapped to streaming DMA on
> line 677:
> dma_addr_t mapping = dma_map_single(..., skb->data, ...);
>
> On line 680, 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 681:
> __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 <[email protected]>

4 patches applied to wireless-drivers-next.git, thanks.

6df3c293d284 rtlwifi: rtl8188ee: avoid accessing the data mapped to streaming DMA
c7ba0ea0df37 rtlwifi: rtl8192ce: avoid accessing the data mapped to streaming DMA
ff7654833894 rtlwifi: rtl8192de: avoid accessing the data mapped to streaming DMA
8b2c13b2e5da rtlwifi: rtl8723ae: avoid accessing the data mapped to streaming DMA

--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches