[PATCH] rtl8192ce: avoid accessing the data mapped to streaming DMA

[PATCH] rtl8192ce: avoid accessing the data mapped to streaming DMA

[Jia-Ju Bai]

In rtl92ce_tx_fill_cmddesc(), skb->data is mapped to streaming DMA on
line 530:
  dma_addr_t mapping = dma_map_single(..., skb->data, ...);

On line 533, 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 534:
  __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 <baijiaju1990@gmail.com>
---
 drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c b/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c
index c0635309a92d..4165175cf5c0 100644
--- a/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c
@@ -527,12 +527,12 @@ void rtl92ce_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

Re: [PATCH] rtl8192ce: avoid accessing the data mapped to streaming DMA

[Pkshih]

On Mon, 2020-10-19 at 11:09 +0800, Jia-Ju Bai wrote:
> In rtl92ce_tx_fill_cmddesc(), skb->data is mapped to streaming DMA on
> line 530:
>   dma_addr_t mapping = dma_map_single(..., skb->data, ...);
> 
> On line 533, 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 534:
>   __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 <baijiaju1990@gmail.com>
> ---
>  drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c
> b/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c
> index c0635309a92d..4165175cf5c0 100644
> --- a/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c
> +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/trx.c
> @@ -527,12 +527,12 @@ void rtl92ce_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");

The changes of the series patches are good to me. 
But, please use 'rtlwifi: ' as subject prefix, like "rtlwifi: rtl8192ce: ...",
and send them as a patchset I think this would be better to maintainer.

Thank you

---
PK

Re: [PATCH] rtl8192ce: avoid accessing the data mapped to streaming DMA

[Kalle Valo]

Jia-Ju Bai <baijiaju1990@gmail.com> wrote:

> In rtl92ce_tx_fill_cmddesc(), skb->data is mapped to streaming DMA on
> line 530:
>   dma_addr_t mapping = dma_map_single(..., skb->data, ...);
> 
> On line 533, 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 534:
>   __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 <baijiaju1990@gmail.com>

Like Ping said, use "rtlwifi:" prefix and have all rtlwifi patches in
the same patchset.

4 patches set to Changes Requested.

11843533 rtl8192ce: avoid accessing the data mapped to streaming DMA
11843541 rtl8192de: avoid accessing the data mapped to streaming DMA
11843553 rtl8723ae: avoid accessing the data mapped to streaming DMA
11843557 rtl8188ee: avoid accessing the data mapped to streaming DMA

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20201019030931.4796-1-baijiaju1990@gmail.com/

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

Re: [PATCH] rtl8192ce: avoid accessing the data mapped to streaming DMA

[Jia-Ju Bai]

On 2020/11/7 19:44, Kalle Valo wrote:
> Jia-Ju Bai <baijiaju1990@gmail.com> wrote:
>
>> In rtl92ce_tx_fill_cmddesc(), skb->data is mapped to streaming DMA on
>> line 530:
>>    dma_addr_t mapping = dma_map_single(..., skb->data, ...);
>>
>> On line 533, 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 534:
>>    __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 <baijiaju1990@gmail.com>
> Like Ping said, use "rtlwifi:" prefix and have all rtlwifi patches in
> the same patchset.
>
> 4 patches set to Changes Requested.
>
> 11843533 rtl8192ce: avoid accessing the data mapped to streaming DMA
> 11843541 rtl8192de: avoid accessing the data mapped to streaming DMA
> 11843553 rtl8723ae: avoid accessing the data mapped to streaming DMA
> 11843557 rtl8188ee: avoid accessing the data mapped to streaming DMA
>

Okay, I have sent v2 patches just now.
Please have a look, thank :)


Best wishes,
Jia-Ju Bai