[PATCH] Xen/gntdev: don't ignore kernel unmapping error

* [PATCH] Xen/gntdev: don't ignore kernel unmapping error
@ 2021-09-17  6:13 Jan Beulich
  2021-09-17  7:35 ` Juergen Gross
  2021-09-20 15:18 ` Juergen Gross
  0 siblings, 2 replies; 3+ messages in thread
From: Jan Beulich @ 2021-09-17  6:13 UTC (permalink / raw)
  To: Juergen Gross, Boris Ostrovsky; +Cc: Stefano Stabellini, lkml, xen-devel

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@suse.com>
---
It is of course questionable whether zapping handles even upon failure
is the best course of action. Otoh unmapping shouldn't normally fail
unless there's a bug elsewhere (which is how I came to notice this
discrepancy).

--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -396,6 +396,14 @@ static int __unmap_grant_pages(struct gn
 			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;
 }


^ permalink raw reply	[flat|nested] 3+ messages in thread