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authorDaniel De Graaf <dgdegra@tycho.nsa.gov>2011-02-10 00:11:32 +0300
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-02-14 22:16:22 +0300
commit12996fc38a2d760f3b30c9ceae26d0eeb92fe52d (patch)
tree2f41f71bff2077360c435c134f1d22217f89958e /drivers/xen/gntdev.c
parentb57c18694ea1641b691fa05ed8af0ce339fa430b (diff)
downloadlinux-12996fc38a2d760f3b30c9ceae26d0eeb92fe52d.tar.xz
xen-gntdev: Avoid double-mapping memory
If an already-mapped area of the device was mapped into userspace a second time, a hypercall was incorrectly made to remap the memory again. Avoid the hypercall on later mmap calls, and fail the mmap call if a writable mapping is attempted on a read-only range. Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/xen/gntdev.c')
-rw-r--r--drivers/xen/gntdev.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 4687cd557c97..2c4cc940c429 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -258,6 +258,9 @@ static int map_grant_pages(struct grant_map *map)
phys_addr_t addr;
if (!use_ptemod) {
+ /* Note: it could already be mapped */
+ if (map->map_ops[0].handle)
+ return 0;
for (i = 0; i < map->count; i++) {
addr = (phys_addr_t)
pfn_to_kaddr(page_to_pfn(map->pages[i]));
@@ -668,9 +671,15 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
if (use_ptemod)
map->vma = vma;
- map->flags = GNTMAP_host_map;
- if (!(vma->vm_flags & VM_WRITE))
- map->flags |= GNTMAP_readonly;
+ if (map->flags) {
+ if ((vma->vm_flags & VM_WRITE) &&
+ (map->flags & GNTMAP_readonly))
+ return -EINVAL;
+ } else {
+ map->flags = GNTMAP_host_map;
+ if (!(vma->vm_flags & VM_WRITE))
+ map->flags |= GNTMAP_readonly;
+ }
spin_unlock(&priv->lock);