Re: cryptoapi incorrect struct page usage

From: David S. Miller (davem@redhat.com)
Date: Sat Aug 09 2003 - 15:41:50 EST


On Sat, 09 Aug 2003 23:33:52 +0300
Mika Penttilä <mika.penttila@xxxxxxxxxxx> wrote:

> sg[elt].page = virt_to_page(skb->data + offset);
> sg[elt].offset = (unsigned long)(skb->data + offset) % PAGE_SIZE;
> sg[elt].length = copy;
>
> so unpinned pages are passed to cryptoapi. Nothing prevents these pages
> from being swapped out. Something like get_user_pages() is needed to pin
> these pages for the duration of crypto operations. Comments?

The page at skb->data was allocated by the skbuff allocation
layer, it has therefore a lifetime the size of the SKB itself.

The crypto API call is finished before we can possibly free up
the SKB, so nothing bad can happen.
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