2020-08-02 13:14:38

by Jia-Ju Bai

Subject: [PATCH] net: vmxnet3: avoid accessing the data mapped to streaming DMA

In vmxnet3_probe_device(), "adapter" is mapped to streaming DMA:
adapter->adapter_pa = dma_map_single(..., adapter, ...);

Then "adapter" is accessed at many places in this function.

Theses accesses may cause data inconsistency between CPU cache and
hardware.

To fix this problem, dma_map_single() is called after these accesses.

Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/net/vmxnet3/vmxnet3_drv.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/net/vmxnet3/vmxnet3_drv.c b/drivers/net/vmxnet3/vmxnet3_drv.c
index ca395f9679d0..96a4c28ba429 100644
--- a/drivers/net/vmxnet3/vmxnet3_drv.c
+++ b/drivers/net/vmxnet3/vmxnet3_drv.c
@@ -3445,14 +3445,6 @@ vmxnet3_probe_device(struct pci_dev *pdev,
}

spin_lock_init(&adapter->cmd_lock);
- adapter->adapter_pa = dma_map_single(&adapter->pdev->dev, adapter,
- sizeof(struct vmxnet3_adapter),
- PCI_DMA_TODEVICE);
- if (dma_mapping_error(&adapter->pdev->dev, adapter->adapter_pa)) {
- dev_err(&pdev->dev, "Failed to map dma\n");
- err = -EFAULT;
- goto err_set_mask;
- }
adapter->shared = dma_alloc_coherent(
&adapter->pdev->dev,
sizeof(struct Vmxnet3_DriverShared),
@@ -3628,6 +3620,16 @@ vmxnet3_probe_device(struct pci_dev *pdev,
}

vmxnet3_check_link(adapter, false);
+
+ adapter->adapter_pa = dma_map_single(&adapter->pdev->dev, adapter,
+ sizeof(struct vmxnet3_adapter),
+ PCI_DMA_TODEVICE);
+ if (dma_mapping_error(&adapter->pdev->dev, adapter->adapter_pa)) {
+ dev_err(&pdev->dev, "Failed to map dma\n");
+ err = -EFAULT;
+ goto err_register;
+ }
+
return 0;

err_register:
@@ -3655,8 +3657,6 @@ vmxnet3_probe_device(struct pci_dev *pdev,
sizeof(struct Vmxnet3_DriverShared),
adapter->shared, adapter->shared_pa);
err_alloc_shared:
- dma_unmap_single(&adapter->pdev->dev, adapter->adapter_pa,
- sizeof(struct vmxnet3_adapter), PCI_DMA_TODEVICE);
err_set_mask:
free_netdev(netdev);
return err;
--
2.17.1

2020-08-03 23:01:01

by David Miller

Subject: Re: [PATCH] net: vmxnet3: avoid accessing the data mapped to streaming DMA

From: Jia-Ju Bai <[email protected]>
Date: Sun, 2 Aug 2020 21:11:07 +0800

> In vmxnet3_probe_device(), "adapter" is mapped to streaming DMA:
> adapter->adapter_pa = dma_map_single(..., adapter, ...);
>
> Then "adapter" is accessed at many places in this function.
>
> Theses accesses may cause data inconsistency between CPU cache and
> hardware.
>
> To fix this problem, dma_map_single() is called after these accesses.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>

'adapter' is accessed everywhere, in the entire driver, not just here
in the probe function.

2020-08-04 02:18:32

by Jia-Ju Bai

Subject: Re: [PATCH] net: vmxnet3: avoid accessing the data mapped to streaming DMA

On 2020/8/4 6:59, David Miller wrote:
> From: Jia-Ju Bai <[email protected]>
> Date: Sun, 2 Aug 2020 21:11:07 +0800
>
>> In vmxnet3_probe_device(), "adapter" is mapped to streaming DMA:
>> adapter->adapter_pa = dma_map_single(..., adapter, ...);
>>
>> Then "adapter" is accessed at many places in this function.
>>
>> Theses accesses may cause data inconsistency between CPU cache and
>> hardware.
>>
>> To fix this problem, dma_map_single() is called after these accesses.
>>
>> Signed-off-by: Jia-Ju Bai <[email protected]>
> 'adapter' is accessed everywhere, in the entire driver, not just here
> in the probe function.

Okay, replacing dma_map_single() with dma_alloc_coherent() may be better.
If you think this solution is okay, I can submit a new patch.


Best wishes,
Jia-Ju Bai