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SubjectRe: [PATCH] virtio-console: avoid DMA from vmalloc area
On Tue, Jul 27, 2021 at 3:13 PM Xianting Tian
<xianting.tian@linux.alibaba.com> 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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