| From: Brian Geffon <bgeffon@google.com> |
| Subject: userfaultfd: fix remap event with MREMAP_DONTUNMAP |
| |
| A user is not required to set a new address when using MREMAP_DONTUNMAP as |
| it can be used without MREMAP_FIXED. When doing so the remap event will |
| use new_addr which may not have been set and we didn't propagate it back |
| other then in the return value of remap_to. |
| |
| Because ret is always the new address it's probably more correct to use it |
| rather than new_addr on the remap_event_complete call, and it resolves |
| this bug. |
| |
| Link: http://lkml.kernel.org/r/20200506172158.218366-1-bgeffon@google.com |
| Fixes: e346b3813067d4b ("mm/mremap: add MREMAP_DONTUNMAP to mremap()") |
| Signed-off-by: Brian Geffon <bgeffon@google.com> |
| Cc: Lokesh Gidra <lokeshgidra@google.com> |
| Cc: Minchan Kim <minchan@kernel.org> |
| Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
| Cc: Vlastimil Babka <vbabka@suse.cz> |
| Cc: "Michael S . Tsirkin" <mst@redhat.com> |
| Cc: Andrea Arcangeli <aarcange@redhat.com> |
| Cc: Sonny Rao <sonnyrao@google.com> |
| Cc: Joel Fernandes <joel@joelfernandes.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| mm/mremap.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/mm/mremap.c~userfaultfd-fix-remap-event-with-mremap_dontunmap |
| +++ a/mm/mremap.c |
| @@ -794,7 +794,7 @@ out: |
| if (locked && new_len > old_len) |
| mm_populate(new_addr + old_len, new_len - old_len); |
| userfaultfd_unmap_complete(mm, &uf_unmap_early); |
| - mremap_userfaultfd_complete(&uf, addr, new_addr, old_len); |
| + mremap_userfaultfd_complete(&uf, addr, ret, old_len); |
| userfaultfd_unmap_complete(mm, &uf_unmap); |
| return ret; |
| } |
| _ |
