# Re: \[PATCH\] virtio-console: avoid DMA from vmalloc area

- From: Arnd Bergmann \<arnd@arndb.de\>
- Date: 2021-07-27 13:20:12 
- List: virtualization
- Page: https://ratatoskr.run/virtualization/2021/07/1459459
- Thread: https://ratatoskr.run/lkml/2021/07/1459452/t.md

```text
On Tue, Jul 27, 2021 at 3:13 PM Xianting Tian
[ref] wrote:
> @@ -1127,13 +1128,18 @@ static int put_chars(u32 vtermno, const char *buf, int count)
>         if (!port)
>                 return -EPIPE;
>
> -       data = kmemdup(buf, count, GFP_ATOMIC);
> -       if (!data)
> -               return -ENOMEM;
> +       if (is_vmalloc_addr(buf)) {
> +               data = kmemdup(buf, count, GFP_ATOMIC);

What about buffers in .data? If those are in a loadable module, I guess you have
the same problem as with vmalloc() and vmap().

is_vmalloc_or_module_addr() would take care of both, not sure if there are
other examples that don't work. In theory it could be ioremap(), kmap_atomic()
or fixmap as well, but those seem less likely to matter here.

        Arnd
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```