Messages in this thread | | | Date | Fri, 17 Oct 2014 13:35:18 +0100 | From | David Vrabel <> | Subject | Re: [Xen-devel] [PATCH V2] xen: avoid race in p2m handling |
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On 17/10/14 12:16, Juergen Gross wrote: > When a new p2m leaf is allocated this leaf is linked into the p2m tree > via cmpxchg. Unfortunately the compare value for checking the success > of the update is read after checking for the need of a new leaf. It is > possible that a new leaf has been linked into the tree concurrently > in between. This could lead to a leaked memory page and to the loss of > some p2m entries. > > Avoid the race by using the read compare value for checking the need > of a new p2m leaf and use ACCESS_ONCE() to get it. > > There are other places which seem to need ACCESS_ONCE() to ensure > proper operation. Change them accordingly.
Applied, thanks.
David
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