[PATCH 07/10] mm: Prevent mprotect from changing shadow stack

From: Yu-cheng Yu
Date: Thu Jun 07 2018 - 11:38:49 EST


Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
---
mm/mprotect.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 625608bc8962..128dcb880c12 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -446,6 +446,15 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
error = -ENOMEM;
if (!vma)
goto out;
+
+ /*
+ * Do not allow changing shadow stack memory.
+ */
+ if (vma->vm_flags & VM_SHSTK) {
+ error = -EINVAL;
+ goto out;
+ }
+
prev = vma->vm_prev;
if (unlikely(grows & PROT_GROWSDOWN)) {
if (vma->vm_start >= end)
--
2.15.1