area->size can include adjacent guard page but get_vm_area_size()
returns actual size of the area.
This fixes possible kernel crash when userspace tries to map area
on 1 page bigger: size check passes but the following vmalloc_to_page()
returns NULL on last guard (non-existing) page.
Signed-off-by: Roman Penyaev <rpenyaev@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
---
mm/vmalloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 871e41c55e23..2cd24186ba84 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2248,7 +2248,7 @@ int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,
if (!(area->flags & VM_USERMAP))
return -EINVAL;
- if (kaddr + size > area->addr + area->size)
+ if (kaddr + size > area->addr + get_vm_area_size(area))
return -EINVAL;
do {
--
2.19.1
