[PATCH -next 0/2] ipc/shm: shmat() fixes around nil-page

[Davidlohr Bueso]

Hi,

These patches fix two issues reported[1] a while back by Joe and Andrea
around how shmat(2) behaves with nil-page.

The first reverts a commit that it was incorrectly thought that mapping
nil-page (address=0) was a no no with MAP_FIXED. This is not the case,
with the exception of SHM_REMAP; which is address in the second patch.

I chose two patches because it is easier to backport and it explicitly
reverts bogus behaviour. Both patches ought to be in -stable and ltp
testcases need updated (the added testcase around the cve can be modified
to just test for SHM_RND|SHM_REMAP).

[1] lkml.kernel.org/r/20180430172152.nfa564pvgpk3ut7p@linux-n805

Thanks! 

Davidlohr Bueso (2):
  Revert "ipc/shm: Fix shmat mmap nil-page protection"
  ipc/shm: fix shmat() nil address after round-down when remapping

 ipc/shm.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

-- 
2.13.6