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: stable@vger.kernel.org Signed-off-by: Juergen Gross jgross@suse.com Reviewed-by: Boris Ostrovsky boris.ostrovsky@oracle.com --- V2: always issue a warning in case xen_destroy_contiguous_region() isn't called (Jan Beulich) --- drivers/xen/swiotlb-xen.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index 5dcb06fe9667..1caadca124b3 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -360,8 +360,8 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr, /* 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);