[RFC PATCH v4 25/27] mm/mmap: Prevent Shadow Stack VMA merges
From: Yu-cheng Yu <hidden>
Date: 2018-09-21 15:11:56
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
memory management, memory mapping, the rest · Maintainers:
Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds
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 <redacted> --- mm/mmap.c | 6 ++++++ 1 file changed, 6 insertions(+)
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
--
2.17.1