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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2015-07-06 23:18:37 +0300
committerMin Chong <mchong@google.com>2016-11-11 01:40:05 +0300
commit0b181e74528cfb9eb38e73ef17634bea3cd8cedc (patch)
treec58d34d0aa5baf22d87107c92ead4d99fe8e7738
parentc72712d1dc116d651e2ec6a0f7d9b41837fb5817 (diff)
downloadlinux-sunxi-mirror/android-3.14.tar.xz
BACKPORT: mm: avoid setting up anonymous pages into file mappingmirror/android-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.c13
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);
}