Commit e5a73150 authored by NeilBrown's avatar NeilBrown Committed by Chuck Lever
Browse files

nfsd: avoid ref leak in nfsd_open_local_fh() 



If two calls to nfsd_open_local_fh() race and both successfully call
nfsd_file_acquire_local(), they will both get an extra reference to the
net to accompany the file reference stored in *pnf.

One of them will fail to store (using xchg()) the file reference in
*pnf and will drop that reference but WON'T drop the accompanying
reference to the net.  This leak means that when the nfs server is shut
down it will hang in nfsd_shutdown_net() waiting for
&nn->nfsd_net_free_done.

This patch adds the missing nfsd_net_put().

Reported-by: default avatarMike Snitzer <snitzer@kernel.org>
Fixes: e6f7e148 ("nfs_localio: simplify interface to nfsd for getting nfsd_file")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarNeilBrown <neil@brown.name>
Tested-by: default avatarMike Snitzer <snitzer@kernel.org>
Reviewed-by: default avatarMike Snitzer <snitzer@kernel.org>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent f9a348e0

fs/nfsd/localio.c

+3 −2
Original line number Diff line number Diff line
@@ -103,10 +103,11 @@ nfsd_open_local_fh(struct net *net, struct auth_domain *dom, 
			if (nfsd_file_get(new) == NULL)

				goto again;

			/*

			 * Drop the ref we were going to install and the

			 * one we were going to return.

			 * Drop the ref we were going to install (both file and

			 * net) and the one we were going to return (only file).

			 */

			nfsd_file_put(localio);

			nfsd_net_put(net);

			nfsd_file_put(localio);

			localio = new;

		}