Commit b57c1869 authored by Daniel De Graaf's avatar Daniel De Graaf Committed by Konrad Rzeszutek Wilk
Browse files

xen-gntdev: Avoid unmapping ranges twice 



In paravirtualized domains, mn_invl_page or mn_invl_range_start can
unmap a segment of a mapped region without unmapping all pages. When
the region is later released, the pages will be unmapped twice, leading
to an incorrect -EINVAL return.

Signed-off-by: default avatarDaniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 84e4075d

drivers/xen/gntdev.c

+31 −2
Original line number Diff line number Diff line
@@ -282,7 +282,7 @@ static int map_grant_pages(struct grant_map *map) 
	return err;

}



static int unmap_grant_pages(struct grant_map *map, int offset, int pages)

static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)

{

	int i, err = 0;
@@ -301,7 +301,6 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages) 
		}

	}



	pr_debug("map %d+%d [%d+%d]\n", map->index, map->count, offset, pages);

	err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);

	if (err)

		return err;
@@ -314,6 +313,36 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages) 
	return err;

}



static int unmap_grant_pages(struct grant_map *map, int offset, int pages)

{

	int range, err = 0;



	pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);



	/* It is possible the requested range will have a "hole" where we

	 * already unmapped some of the grants. Only unmap valid ranges.

	 */

	while (pages && !err) {

		while (pages && !map->unmap_ops[offset].handle) {

			offset++;

			pages--;

		}

		range = 0;

		while (range < pages) {

			if (!map->unmap_ops[offset+range].handle) {

				range--;

				break;

			}

			range++;

		}

		err = __unmap_grant_pages(map, offset, range);

		offset += range;

		pages -= range;

	}



	return err;

}



/* ------------------------------------------------------------------ */



static void gntdev_vma_close(struct vm_area_struct *vma)

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