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

[Jia-Ju Bai]

Thanks for the advice.
I have added the description of the changes and resent the patches.


Best wishes,
Jia-Ju Bai

On 2020/11/19 1:20, Larry Finger wrote:
> On 11/17/20 7:53 PM, Jia-Ju Bai 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 <baijiaju1990@xxxxxxxxx>
> > ---
> >   drivers/net/wireless/realtek/rtlwifi/rtl8188ee/trx.c | 6 +++---
> >   1 file changed, 3 insertions(+), 3 deletions(-)
>
> What changed between v1 and v2?
>
> As outlined in Documentation/process/submitting-patches.rst, you 
> should add a '---' marker and descrive what was changed. I usually 
> summarize the changes, but it is also possible to provide a diffstat 
> of the changes as the above file shows.