vm audit: add VM_DONTEXPAND to mmap for drivers that need it

Drivers that register a ->fault handler, but do not range-check the
offset argument, must set VM_DONTEXPAND in the vm_flags in order to
prevent an expanding mremap from overflowing the resource.

I've audited the tree and attempted to fix these problems (usually by
adding VM_DONTEXPAND where it is not obvious).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index d2b6d44..8295577 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2216,7 +2216,7 @@ int install_special_mapping(struct mm_struct *mm,
 	vma->vm_start = addr;
 	vma->vm_end = addr + len;
 
-	vma->vm_flags = vm_flags | mm->def_flags;
+	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
 	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 
 	vma->vm_ops = &special_mapping_vmops;