[PATCH AUTOSEL 5.14 28/40] Xen/gntdev: don't ignore kernel unmapping error

[Sasha Levin <sashal@xxxxxxxxxx>]

From: Jan Beulich <jbeulich@xxxxxxxx>

[ Upstream commit f28347cc66395e96712f5c2db0a302ee75bafce6 ]

While working on XSA-361 and its follow-ups, I failed to spot another
place where the kernel mapping part of an operation was not treated the
same as the user space part. Detect and propagate errors and add a 2nd
pr_debug().

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Link: https://lore.kernel.org/r/c2513395-74dc-aea3-9192-fd265aa44e35@xxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/xen/gntdev.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index a3e7be96527d..23fd09a9bbaf 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -396,6 +396,14 @@ static int __unmap_grant_pages(struct gntdev_grant_map 
*map, int offset,
                        map->unmap_ops[offset+i].handle,
                        map->unmap_ops[offset+i].status);
                map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
+               if (use_ptemod) {
+                       if (map->kunmap_ops[offset+i].status)
+                               err = -EINVAL;
+                       pr_debug("kunmap handle=%u st=%d\n",
+                                map->kunmap_ops[offset+i].handle,
+                                map->kunmap_ops[offset+i].status);
+                       map->kunmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
+               }
        }
        return err;
 }
-- 
2.33.0