UPSTREAM: 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.
Fixes: e346b3813067d4b ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Brian Geffon <bgeffon@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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>
Link: http://lkml.kernel.org/r/20200506172158.218366-1-bgeffon@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit d1564926066115fb47ca06b2b9d23ed506ca9608)
Bug: 176847609
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Change-Id: I7a20139ee14a2c9124b74310d7c0324c11009087
diff --git a/mm/mremap.c b/mm/mremap.c
index 9ef41fd..0bd03cf 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -699,7 +699,7 @@
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;
}