From: Juergen Gross <[email protected]> commit 50f6393f9654c561df4cdcf8e6cfba7260143601 upstream.
The condition in xen_swiotlb_free_coherent() for deciding whether to call xen_destroy_contiguous_region() is wrong: in case the region to be freed is not contiguous calling xen_destroy_contiguous_region() is the wrong thing to do: it would result in inconsistent mappings of multiple PFNs to the same MFN. This will lead to various strange crashes or data corruption. Instead of calling xen_destroy_contiguous_region() in that case a warning should be issued as that situation should never occur. Cc: [email protected] Signed-off-by: Juergen Gross <[email protected]> Reviewed-by: Boris Ostrovsky <[email protected]> Reviewed-by: Jan Beulich <[email protected]> Acked-by: Konrad Rzeszutek Wilk <[email protected]> Signed-off-by: Juergen Gross <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/xen/swiotlb-xen.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -371,8 +371,8 @@ xen_swiotlb_free_coherent(struct device /* Convert the size to actually allocated. */ size = 1UL << (order + XEN_PAGE_SHIFT); - if (((dev_addr + size - 1 <= dma_mask)) || - range_straddles_page_boundary(phys, size)) + if (!WARN_ON((dev_addr + size - 1 > dma_mask) || + range_straddles_page_boundary(phys, size))) xen_destroy_contiguous_region(phys, order); xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);
