atm: eni: avoid accessing the data mapped to streaming DMA (a45a9e8a) · Commits · 戴 / test

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>

drivers/atm/eni.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -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_pos4));*/
		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);

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