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atm: eni: avoid accessing the data mapped to streaming DMA 

In do_tx(), skb->data is mapped to streaming DMA on line 1111:
  paddr = dma_map_single(...,skb->data,DMA_TO_DEVICE);

Then skb->data is accessed on line 1153:
  (skb->data[3] & 0xf)

This access may cause data inconsistency between CPU cache and hardware.

To fix this problem, skb->data[3] is assigned to a local variable before
DMA mapping, and then the driver accesses this local variable instead of
skb->data[3].

Signed-off-by: Jia-Ju Bai <baijiaju@tsinghua.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jia-Ju Bai 2020-08-02 17:16:11 +08:00 committed by David S. Miller
parent 6d78e473e0
commit a45a9e8a76
1 changed files with 3 additions and 1 deletions
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4
drivers/atm/eni.c
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@ -1034,6 +1034,7 @@ static enum enq_res do_tx(struct sk_buff *skb)
u32 dma_rd,dma_wr;
u32 size; /* in words */
int aal5,dma_size,i,j;
unsigned char skb_data3;
DPRINTK(">do_tx\n");
NULLCHECK(skb);
@ -1108,6 +1109,7 @@ DPRINTK("iovcnt = %d\n",skb_shinfo(skb)->nr_frags);
vcc->dev->number);
return enq_jam;
}
skb_data3 = skb->data[3];
paddr = dma_map_single(&eni_dev->pci_dev->dev,skb->data,skb->len,
DMA_TO_DEVICE);
ENI_PRV_PADDR(skb) = paddr;
@ -1150,7 +1152,7 @@ DPRINTK("doing direct send\n"); /* @@@ well, this doesn't work anyway */
(size/(ATM_CELL_PAYLOAD/4)),tx->send+tx->tx_pos*4);
/*printk("dsc = 0x%08lx\n",(unsigned long) readl(tx->send+tx->tx_pos*4));*/
writel((vcc->vci << MID_SEG_VCI_SHIFT) |
(aal5 ? 0 : (skb->data[3] & 0xf)) |
(aal5 ? 0 : (skb_data3 & 0xf)) |
(ATM_SKB(skb)->atm_options & ATM_ATMOPT_CLP ? MID_SEG_CLP : 0),
tx->send+((tx->tx_pos+1) & (tx->words-1))*4);
DPRINTK("size: %d, len:%d\n",size,skb->len);