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xen/gntdev: avoid out of bounds access in case of partial gntdev_mmap()

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commit 298d275d4d9bea3524ff4bc76678c140611d8a8d upstream.

In case gntdev_mmap() succeeds only partially in mapping grant pages
it will leave some vital information uninitialized needed later for
cleanup. This will lead to an out of bounds array access when unmapping
the already mapped pages.

So just initialize the data needed for unmapping the pages a little bit
earlier.

Reported-by: Arthur Borsboom <arthurborsboom@gmail.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Juergen Gross 2017-10-25 17:08:07 +02:00 committed by Greg Kroah-Hartman
parent 82e05e935f
commit 8b396ff8ee
1 changed files with 1 additions and 1 deletions
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2
drivers/xen/gntdev.c
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@ -827,6 +827,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
mutex_unlock(&priv->lock);
if (use_ptemod) {
map->pages_vm_start = vma->vm_start;
err = apply_to_page_range(vma->vm_mm, vma->vm_start,
vma->vm_end - vma->vm_start,
find_grant_ptes, map);
@ -864,7 +865,6 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
set_grant_ptes_as_special, NULL);
}
#endif
map->pages_vm_start = vma->vm_start;
}
return 0;