diff mbox series

[RFC,v4,25/27] mm/mmap: Prevent Shadow Stack VMA merges

Message ID 20180921150351.20898-26-yu-cheng.yu@intel.com (mailing list archive)
State New, archived
Headers show
Series Control Flow Enforcement: Shadow Stack | expand

Commit Message

Yu-cheng Yu Sept. 21, 2018, 3:03 p.m. UTC 
Function returns could unwind stacks beyond its allocated area.
We do not merge shadow stack areas.

This and VMA guards prevent shadow stack underflow.

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

Patch

diff --git a/mm/mmap.c b/mm/mmap.c
index de2d0faa1c61..fa581ced3f56 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1123,6 +1123,12 @@  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