From: "J. Bruce Fields" <bfields@xxxxxxxxxx> [ Upstream commit 62a063b8e7d1db684db3f207261a466fa3194e72 ] Anatoly Trosinenko reports that this: 1) Checkout fresh master Linux branch (tested with commit e195ca6cb) 2) Copy x84_64-config-4.14 to .config, then enable NFS server v4 and build 3) From `kvm-xfstests shell`: results in NULL dereference in locks_end_grace. Check that nfsd has been started before trying to end the grace period. Reported-by: Anatoly Trosinenko <anatoly.trosinenko@xxxxxxxxx> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/nfsd/nfsctl.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 6384c9b94898..b33f9785b756 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1126,6 +1126,8 @@ static ssize_t write_v4_end_grace(struct file *file, char *buf, size_t size) case 'Y': case 'y': case '1': + if (nn->nfsd_serv) + return -EBUSY; nfsd4_end_grace(nn); break; default: -- 2.19.1
