From 5fa4e6f1c2d8c9a4e47e1931b42893172d388f2b Mon Sep 17 00:00:00 2001
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Date: Thu, 13 Aug 2020 09:21:09 +0300
Subject: [PATCH] xen/gntdev: Fix dmabuf import with non-zero sgt offset
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>
Link: https://lore.kernel.org/r/20200813062113.11030-2-andr2000@gmail.com
Signed-off-by: Juergen Gross <jgross@suse.com>
---
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);