[PATCH 08/10] mm: Prevent mremap of shadow stack

From: Yu-cheng Yu
Date: Thu Jun 07 2018 - 10:41:52 EST


Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
---
mm/mremap.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 049470aa1e3e..70f20edb248e 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -525,7 +525,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
unsigned long, new_addr)
{
struct mm_struct *mm = current->mm;
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma = find_vma(mm, addr);
unsigned long ret = -EINVAL;
unsigned long charged = 0;
bool locked = false;
@@ -533,6 +533,9 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
LIST_HEAD(uf_unmap_early);
LIST_HEAD(uf_unmap);

+ if (vma->vm_flags & VM_SHSTK)
+ return ret;
+
if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
return ret;

--
2.15.1