mm/mremap: write-lock VMA while remapping it to a new address range

Write-lock VMA as locked before copying it and when copy_vma produces a
new VMA.

Link: https://lkml.kernel.org/r/20230227173632.3292573-18-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Laurent Dufour <laurent.dufour@fr.ibm.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index 82999e0c3c31932223842a420ec13b226560b64c..8ba51e73f6265b9febf97ea3bc4f060332d6e673 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3197,6 +3197,7 @@ 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);
                if (vma_link(mm, new_vma))
                        goto out_vma_link;
                *need_rmap_locks = false;

diff --git a/mm/mremap.c b/mm/mremap.c
index 0eaa11c845b9d0033c3a5f81e4ac50c27837d31e..b11ce6c920996d99f21145cd7fd4215e0a3c5beb 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -623,6 +623,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
                        return -ENOMEM;
        }
 
+       vma_start_write(vma);
        new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
        new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
                           &need_rmap_locks);