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author | NeilBrown <neilb@suse.com> | 2019-03-19 03:33:24 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-03 07:26:21 +0300 |
commit | da57cba4f3f1c63303cffcee97cf4d7bf1ff386a (patch) | |
tree | c38880c4648e2bfb2695e6d94c89ed0361f0cbf8 /fs/nfs/nfs4proc.c | |
parent | 0f273f0c3064dab95c82d6046b0f5ea2ababd304 (diff) | |
download | linux-da57cba4f3f1c63303cffcee97cf4d7bf1ff386a.tar.xz |
NFS: fix mount/umount race in nlmclnt.
commit 4a9be28c45bf02fa0436808bb6c0baeba30e120e upstream.
If the last NFSv3 unmount from a given host races with a mount from the
same host, we can destroy an nlm_host that is still in use.
Specifically nlmclnt_lookup_host() can increment h_count on
an nlm_host that nlmclnt_release_host() has just successfully called
refcount_dec_and_test() on.
Once nlmclnt_lookup_host() drops the mutex, nlm_destroy_host_lock()
will be called to destroy the nlmclnt which is now in use again.
The cause of the problem is that the dec_and_test happens outside the
locked region. This is easily fixed by using
refcount_dec_and_mutex_lock().
Fixes: 8ea6ecc8b075 ("lockd: Create client-side nlm_host cache")
Cc: stable@vger.kernel.org (v2.6.38+)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/nfs/nfs4proc.c')
0 files changed, 0 insertions, 0 deletions