diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2015-08-25 14:32:00 +1000 |
|---|---|---|
| committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2015-08-27 17:14:59 +1000 |
| commit | cc9fc8e621ad966c4cbeee127c1b8bfc8c09f2ca (patch) | |
| tree | 4e0feca139ebfa6a430788eb77c8d205296f7988 | |
| parent | 344ccce1bd65511e4f9cac4d2a4c2c4943ff6aed (diff) | |
mm: make sure all file VMAs have ->vm_ops set
We rely on vma->vm_ops == NULL to detect anonymous VMA: see
vma_is_anonymous(), but some drivers doesn't set ->vm_ops.
As a result we can end up with anonymous page in private file mapping.
That should not lead to serious misbehaviour, but nevertheless is wrong.
Let's fix by setting up dummy ->vm_ops for file mmapping if f_op->mmap()
didn't set its own.
The patch also adds sanity check into __vma_link_rb(). It will help
catch broken VMAs which inserted directly into mm_struct via
insert_vm_struct().
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/mmap.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 2957084fdff1..df6d5f07035b 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -612,6 +612,8 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm, void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, struct rb_node **rb_link, struct rb_node *rb_parent) { + WARN_ONCE(vma->vm_file && !vma->vm_ops, "missing vma->vm_ops"); + /* Update tracking information for the gap following the new vma. */ if (vma->vm_next) vma_gap_update(vma->vm_next); @@ -1636,6 +1638,12 @@ unsigned long mmap_region(struct file *file, unsigned long addr, */ WARN_ON_ONCE(addr != vma->vm_start); + /* All file mapping must have ->vm_ops set */ + if (!vma->vm_ops) { + static const struct vm_operations_struct dummy_ops = {}; + vma->vm_ops = &dummy_ops; + } + addr = vma->vm_start; vm_flags = vma->vm_flags; } else if (vm_flags & VM_SHARED) { |