* Suren Baghdasaryan surenb@google.com [230801 18:07]:
While it's not strictly necessary to lock a newly created vma before adding it into the vma tree (as long as no further changes are performed to it), it seems like a good policy to lock it and prevent accidental changes after it becomes visible to the page faults. Lock the vma before adding it into the vma tree.
Suggested-by: Jann Horn jannh@google.com Signed-off-by: Suren Baghdasaryan surenb@google.com
Reviewed-by: Liam R. Howlett Liam.Howlett@oracle.com
mm/mmap.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c index 3937479d0e07..850a39dee075 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -412,6 +412,8 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma) if (vma_iter_prealloc(&vmi)) return -ENOMEM;
- vma_start_write(vma);
- if (vma->vm_file) { mapping = vma->vm_file->f_mapping; i_mmap_lock_write(mapping);
@@ -477,7 +479,8 @@ static inline void vma_prepare(struct vma_prepare *vp) vma_start_write(vp->vma); if (vp->adj_next) vma_start_write(vp->adj_next);
- /* vp->insert is always a newly created VMA, no need for locking */
- if (vp->insert)
vma_start_write(vp->insert);@@ -3098,6 +3101,7 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma, vma->vm_pgoff = addr >> PAGE_SHIFT; vm_flags_init(vma, flags); vma->vm_page_prot = vm_get_page_prot(flags);
- vma_start_write(vma); if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL)) goto mas_store_fail;
@@ -3345,7 +3349,6 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, get_file(new_vma->vm_file); if (new_vma->vm_ops && new_vma->vm_ops->open) new_vma->vm_ops->open(new_vma);
vma_start_write(new_vma);-- 2.41.0.585.gd2178a4bd4-goog