mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
synced 2024-12-25 07:29:24 -05:00
77 lines
2.6 KiB
Diff
77 lines
2.6 KiB
Diff
From 6b7339f4c31ad69c8e9c0b2859276e22cf72176d Mon Sep 17 00:00:00 2001
|
|
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
|
|
Date: Mon, 6 Jul 2015 23:18:37 +0300
|
|
Subject: mm: avoid setting up anonymous pages into file mapping
|
|
|
|
Reading page fault handler code I've noticed that under right
|
|
circumstances kernel would map anonymous pages into file mappings: if
|
|
the VMA doesn't have vm_ops->fault() and the VMA wasn't fully populated
|
|
on ->mmap(), kernel would handle page fault to not populated pte with
|
|
do_anonymous_page().
|
|
|
|
Let's change page fault handler to use do_anonymous_page() only on
|
|
anonymous VMA (->vm_ops == NULL) and make sure that the VMA is not
|
|
shared.
|
|
|
|
For file mappings without vm_ops->fault() or shred VMA without vm_ops,
|
|
page fault on pte_none() entry would lead to SIGBUS.
|
|
|
|
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
|
|
Acked-by: Oleg Nesterov <oleg@redhat.com>
|
|
Cc: Andrew Morton <akpm@linux-foundation.org>
|
|
Cc: Willy Tarreau <w@1wt.eu>
|
|
Cc: stable@vger.kernel.org
|
|
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
---
|
|
mm/memory.c | 20 +++++++++++++-------
|
|
1 file changed, 13 insertions(+), 7 deletions(-)
|
|
|
|
diff --git a/mm/memory.c b/mm/memory.c
|
|
index a84fbb7..388dcf9 100644
|
|
--- a/mm/memory.c
|
|
+++ b/mm/memory.c
|
|
@@ -2670,6 +2670,10 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
|
|
pte_unmap(page_table);
|
|
|
|
+ /* File mapping without ->vm_ops ? */
|
|
+ if (vma->vm_flags & VM_SHARED)
|
|
+ return VM_FAULT_SIGBUS;
|
|
+
|
|
/* Check if we need to add a guard page to the stack */
|
|
if (check_stack_guard_page(vma, address) < 0)
|
|
return VM_FAULT_SIGSEGV;
|
|
@@ -3099,6 +3103,9 @@ static int do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
|
|
|
|
pte_unmap(page_table);
|
|
+ /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
|
|
+ if (!vma->vm_ops->fault)
|
|
+ return VM_FAULT_SIGBUS;
|
|
if (!(flags & FAULT_FLAG_WRITE))
|
|
return do_read_fault(mm, vma, address, pmd, pgoff, flags,
|
|
orig_pte);
|
|
@@ -3244,13 +3251,12 @@ static int handle_pte_fault(struct mm_struct *mm,
|
|
barrier();
|
|
if (!pte_present(entry)) {
|
|
if (pte_none(entry)) {
|
|
- if (vma->vm_ops) {
|
|
- if (likely(vma->vm_ops->fault))
|
|
- return do_fault(mm, vma, address, pte,
|
|
- pmd, flags, entry);
|
|
- }
|
|
- return do_anonymous_page(mm, vma, address,
|
|
- pte, pmd, flags);
|
|
+ if (vma->vm_ops)
|
|
+ return do_fault(mm, vma, address, pte, pmd,
|
|
+ flags, entry);
|
|
+
|
|
+ return do_anonymous_page(mm, vma, address, pte, pmd,
|
|
+ flags);
|
|
}
|
|
return do_swap_page(mm, vma, address,
|
|
pte, pmd, flags, entry);
|
|
--
|
|
cgit v1.1
|
|
|