4.9-stable review patch. If anyone has any objections, please let me know.
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[ 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@gmail.com Signed-off-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfsd/nfsctl.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 36b2af931e06..797a155c9a67 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1103,6 +1103,8 @@ 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: