[RFC PATCH v6 09/26] mm/mmap: Prevent Shadow Stack VMA merges

Yu-cheng Yu
2018-11-19T21:47:52Z

To prevent function call/return spills into the next shadow stack
area, do not merge shadow stack areas.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
mm/mmap.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index 6c04292e16a7..30836512ca79 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1147,6 +1147,12 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
if (vm_flags & VM_SPECIAL)
return NULL;

+ /*
+ * Do not merge shadow stack areas.
+ */
+ if (vm_flags & VM_SHSTK)
+ return NULL;
+
if (prev)
next = prev->vm_next;
else
--
2.17.1