Re: [Xen-devel] [PATCH] x86/mm: fix invalid unlinking of nested p2m tables

[Tim Deegan <tim@xxxxxxx>]

At 18:16 +1300 on 28 Feb (1362075364), Matthew Daley wrote:
> Commit 90805dc (c/s 26387:4056e5a3d815) ("EPT: Make ept data stucture or
> operations neutral") makes nested p2m tables be unlinked from the host
> p2m table before their destruction (in p2m_teardown_nestedp2m).
> However, by this time the host p2m table has already been torn down,
> leading to a possible race condition where another allocation between
> the two kinds of table being torn down can lead to a linked list
> assertion with debug=y builds or memory corruption on debug=n ones.
> 
> Fix by swapping the order the two kinds of table are torn down in. While
> at it, remove the condition in p2m_final_teardown, as it is already
> checked identically in p2m_teardown_hostp2m itself.
> 
> Signed-off-by: Matthew Daley <mattjd@xxxxxxxxx>

Applied, thanks.

Tim.

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