mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
synced 2024-12-22 14:14:58 -05:00
74 lines
2.5 KiB
Diff
74 lines
2.5 KiB
Diff
|
From e2506476534cff7bb3697fbe0654fdefd101bc80 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
|
||
|
|
|
||
|
|
commit 6b7339f4c31ad69c8e9c0b2859276e22cf72176d upstream.
|
||
|
|
|
||
|
|
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>
|
||
|
|
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
|
[bwh: Backported to 3.2: adjust context]
|
||
|
|
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
||
|
|
---
|
||
|
|
mm/memory.c | 13 +++++++++----
|
||
|
|
1 file changed, 9 insertions(+), 4 deletions(-)
|
||
|
|
|
||
|
|
diff --git a/mm/memory.c b/mm/memory.c
|
||
|
|
index 452b8ba..7762b1d 100644
|
||
|
|
--- a/mm/memory.c
|
||
|
|
+++ b/mm/memory.c
|
||
|
|
@@ -3153,6 +3153,10 @@ 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;
|
||
|
|
@@ -3412,6 +3416,9 @@ static int do_linear_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;
|
||
|
|
return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
|
||
|
|
}
|
||
|
|
|
||
|
|
@@ -3470,11 +3477,9 @@ int handle_pte_fault(struct mm_struct *mm,
|
||
|
|
entry = *pte;
|
||
|
|
if (!pte_present(entry)) {
|
||
|
|
if (pte_none(entry)) {
|
||
|
|
- if (vma->vm_ops) {
|
||
|
|
- if (likely(vma->vm_ops->fault))
|
||
|
|
- return do_linear_fault(mm, vma, address,
|
||
|
|
+ if (vma->vm_ops)
|
||
|
|
+ return do_linear_fault(mm, vma, address,
|
||
|
|
pte, pmd, flags, entry);
|
||
|
|
- }
|
||
|
|
return do_anonymous_page(mm, vma, address,
|
||
|
|
pte, pmd, flags);
|
||
|
|
}
|
||
|
|
--
|
||
|
|
cgit v1.1
|
||
|
|
|