From: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com

It is possible that the scatter-gather table during dmabuf import has non-zero offset of the data, but user-space doesn't expect that. Fix this by failing the import, so user-space doesn't access wrong data.

Fixes: bf8dc55b1358 ("xen/gntdev: Implement dma-buf import functionality")

Signed-off-by: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com Acked-by: Juergen Gross jgross@suse.com Cc: stable@vger.kernel.org --- drivers/xen/gntdev-dmabuf.c | 8 ++++++++ 1 file changed, 8 insertions(+)

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c index 75d3bb948bf3..b1b6eebafd5d 100644 --- a/drivers/xen/gntdev-dmabuf.c +++ b/drivers/xen/gntdev-dmabuf.c @@ -613,6 +613,14 @@ dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev, goto fail_detach; }

+ /* Check that we have zero offset. */ + if (sgt->sgl->offset) { + ret = ERR_PTR(-EINVAL); + pr_debug("DMA buffer has %d bytes offset, user-space expects 0\n", + sgt->sgl->offset); + goto fail_unmap; + } + /* Check number of pages that imported buffer has. */ if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) { ret = ERR_PTR(-EINVAL);