diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2015-07-06 23:18:37 +0300 |
|---|---|---|
| committer | Min Chong <mchong@google.com> | 2016-11-10 14:40:05 -0800 |
| commit | 0b181e74528cfb9eb38e73ef17634bea3cd8cedc (patch) | |
| tree | c58d34d0aa5baf22d87107c92ead4d99fe8e7738 | |
| parent | c72712d1dc116d651e2ec6a0f7d9b41837fb5817 (diff) | |
| download | common-android-3.14.tar.gz | |
BACKPORT: mm: avoid setting up anonymous pages into file mappingdeprecated/android-3.14android-3.14
(cherry picked from commit 6b7339f4c31ad69c8e9c0b2859276e22cf72176d)
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>
Change-Id: I451f90075ddf0c3592543e4fe30eed4c38348d49
Bug: 32460277
| -rw-r--r-- | mm/memory.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/mm/memory.c b/mm/memory.c index 22dfa617bddb..86c09a8284cd 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3228,6 +3228,10 @@ 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_SIGBUS; @@ -3496,6 +3500,9 @@ 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); } @@ -3644,11 +3651,9 @@ static 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); } |