On 08/20/2018 10:53 AM, Verma, Vishal L wrote:
>
> On Mon, 2018-08-13 at 20:02 +0800, Zhang Yi wrote:
>> This patch prevents a user mapping an illegal vma range that is larger
>> than a dax device physical resource.
>>
>> When qemu maps the dax device for virtual nvdimm's backend device, the
>> v-nvdimm label area is defined at the end of mapped range. By using an
>> illegal size that exceeds the range of the device dax, it will trigger a
>> fault with qemu.
>>
>> Signed-off-by: Zhang Yi <[email protected]>
>> ---
>> drivers/dax/device.c | 29 +++++++++++++++++++++++++++++
>> 1 file changed, 29 insertions(+)
>>
>
> Looks good to me:
> Reviewed-by: Vishal Verma <[email protected]>
Applied.
>
>> diff --git a/drivers/dax/device.c b/drivers/dax/device.c
>> index 108c37f..6fe8c30 100644
>> --- a/drivers/dax/device.c
>> +++ b/drivers/dax/device.c
>> @@ -177,6 +177,33 @@ static const struct attribute_group
>> *dax_attribute_groups[] = {
>> NULL,
>> };
>>
>> +static int check_vma_range(struct dev_dax *dev_dax, struct vm_area_struct
>> *vma,
>> + const char *func)
>> +{
>> + struct device *dev = &dev_dax->dev;
>> + struct resource *res;
>> + unsigned long size;
>> + int ret, i;
>> +
>> + if (!dax_alive(dev_dax->dax_dev))
>> + return -ENXIO;
>> +
>> + size = vma->vm_end - vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT);
>> + ret = -EINVAL;
>> + for (i = 0; i < dev_dax->num_resources; i++) {
>> + res = &dev_dax->res[i];
>> + if (size > resource_size(res)) {
>> + dev_info_ratelimited(dev,
>> + "%s: %s: fail, vma range overflow\n",
>> + current->comm, func);
>> + ret = -EINVAL;
>> + continue;
>> + } else
>> + return 0;
>> + }
>> + return ret;
>> +}
>> +
>> static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
>> const char *func)
>> {
>> @@ -469,6 +496,8 @@ static int dax_mmap(struct file *filp, struct
>> vm_area_struct *vma)
>> */
>> id = dax_read_lock();
>> rc = check_vma(dev_dax, vma, __func__);
>> + if (!rc)
>> + rc = check_vma_range(dev_dax, vma, __func__);
>> dax_read_unlock(id);
>> if (rc)
>> return rc;
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