4.9-stable review patch. If anyone has any objections, please let me know.
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From: Joe Jin joe.jin@oracle.com
commit 7250f422da0480d8512b756640f131b9b893ccda upstream.
xen_swiotlb_{alloc,free}_coherent() allocate/free memory based on the order of the pages and not size argument (bytes). This is inconsistent with range_straddles_page_boundary and memset which use the 'size' value, which may lead to not exchanging memory with Xen (range_straddles_page_boundary() returned true). And then the call to xen_swiotlb_free_coherent() would actually try to exchange the memory with Xen, leading to the kernel hitting an BUG (as the hypercall returned an error).
This patch fixes it by making the 'size' variable be of the same size as the amount of memory allocated.
CC: stable@vger.kernel.org Signed-off-by: Joe Jin joe.jin@oracle.com Cc: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Cc: Boris Ostrovsky boris.ostrovsky@oracle.com Cc: Christoph Helwig hch@lst.de Cc: Dongli Zhang dongli.zhang@oracle.com Cc: John Sobecki john.sobecki@oracle.com Signed-off-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/xen/swiotlb-xen.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -310,6 +310,9 @@ xen_swiotlb_alloc_coherent(struct device */ flags &= ~(__GFP_DMA | __GFP_HIGHMEM);
+ /* Convert the size to actually allocated. */ + size = 1UL << (order + XEN_PAGE_SHIFT); + /* On ARM this function returns an ioremap'ped virtual address for * which virt_to_phys doesn't return the corresponding physical * address. In fact on ARM virt_to_phys only works for kernel direct @@ -359,6 +362,9 @@ xen_swiotlb_free_coherent(struct device * physical address */ phys = xen_bus_to_phys(dev_addr);
+ /* 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)) xen_destroy_contiguous_region(phys, order);