[RFC PATCH v4 24/27] mm/mmap: Create a guard area between VMAs
From: Yu-cheng Yu <hidden>
Date: 2018-09-21 15:10:29
Also in:
linux-api, linux-doc, linux-mm, lkml
Subsystem:
memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
Create a guard area between VMAs, to detect memory corruption. Signed-off-by: Yu-cheng Yu <redacted> --- include/linux/mm.h | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c4cc07baccda..3a823bdae09d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -2443,24 +2443,34 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m static inline unsigned long vm_start_gap(struct vm_area_struct *vma) { unsigned long vm_start = vma->vm_start; + unsigned long gap; + + if (vma->vm_flags & VM_GROWSDOWN) + gap = stack_guard_gap; + else + gap = PAGE_SIZE; + + vm_start -= gap; + if (vm_start > vma->vm_start) + vm_start = 0; - if (vma->vm_flags & VM_GROWSDOWN) { - vm_start -= stack_guard_gap; - if (vm_start > vma->vm_start) - vm_start = 0; - } return vm_start; } static inline unsigned long vm_end_gap(struct vm_area_struct *vma) { unsigned long vm_end = vma->vm_end; + unsigned long gap; + + if (vma->vm_flags & VM_GROWSUP) + gap = stack_guard_gap; + else + gap = PAGE_SIZE; + + vm_end += gap; + if (vm_end < vma->vm_end) + vm_end = -PAGE_SIZE; - if (vma->vm_flags & VM_GROWSUP) { - vm_end += stack_guard_gap; - if (vm_end < vma->vm_end) - vm_end = -PAGE_SIZE; - } return vm_end; }
--
2.17.1