nfs: fix potential credential leak in ff_layout_update_mirror_cred
authorJeff Layton <jlayton@poochiereds.net>
Wed, 24 Jun 2015 16:10:23 +0000 (12:10 -0400)
committerTrond Myklebust <trond.myklebust@primarydata.com>
Thu, 25 Jun 2015 23:34:40 +0000 (19:34 -0400)
commita24221dca1868101c9b4b5adde4a6a5b1a3a64a7
treef8436d89c3ab895df0cc70579c45e6140bd27d17
parent1372a3130a3e0bfd38d82d476f0a907cc72ba816
nfs: fix potential credential leak in ff_layout_update_mirror_cred

If we have two tasks racing to update a mirror's credentials, then they
can end up leaking one (or more) sets of credentials. The first task
will set mirror->cred and then the second task will just overwrite it.

Use a cmpxchg to ensure that the creds are only set once. If we get to
the point where we would set mirror->cred and find that they're already
set, then we just release the creds that were just found.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
fs/nfs/flexfilelayout/flexfilelayoutdev.c