NFSD: fix problems with cleanup on errors in nfsd4_copy

When nfsd4_copy fails to allocate memory for async_copy->cp_src, or
nfs4_init_copy_state fails, it calls cleanup_async_copy to do the
cleanup for the async_copy which causes page fault since async_copy
is not yet initialized.

This patche rearranges the order of initializing the fields in
async_copy and adds checks in cleanup_async_copy to skip un-initialized
fields.

Fixes: ce0887ac ("NFSD add nfs4 inter ssc to nfsd4_copy")
Fixes: 87689df6 ("NFSD: Shrink size of struct nfsd4_copy")
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4proc.c

@@ -1687,9 +1687,12 @@ static void cleanup_async_copy(struct nfsd4_copy *copy)
 {
 	nfs4_free_copy_state(copy);
 	release_copy_files(copy);
-	spin_lock(&copy->cp_clp->async_lock);
-	list_del(&copy->copies);
-	spin_unlock(&copy->cp_clp->async_lock);
+	if (copy->cp_clp) {
+		spin_lock(&copy->cp_clp->async_lock);
+		if (!list_empty(&copy->copies))
+			list_del_init(&copy->copies);
+		spin_unlock(&copy->cp_clp->async_lock);
+	}
 	nfs4_put_copy(copy);
 }
 
@@ -1786,12 +1789,13 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		async_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL);
 		if (!async_copy)
 			goto out_err;
+		INIT_LIST_HEAD(&async_copy->copies);
+		refcount_set(&async_copy->refcount, 1);
 		async_copy->cp_src = kmalloc(sizeof(*async_copy->cp_src), GFP_KERNEL);
 		if (!async_copy->cp_src)
 			goto out_err;
 		if (!nfs4_init_copy_state(nn, copy))
 			goto out_err;
-		refcount_set(&async_copy->refcount, 1);
 		memcpy(&copy->cp_res.cb_stateid, &copy->cp_stateid.cs_stid,
 			sizeof(copy->cp_res.cb_stateid));
 		dup_copy_fields(copy, async_copy);

fs/nfsd/nfs4state.c

@@ -975,7 +975,6 @@ static int nfs4_init_cp_state(struct nfsd_net *nn, copy_stateid_t *stid,
 
 	stid->cs_stid.si_opaque.so_clid.cl_boot = (u32)nn->boot_time;
 	stid->cs_stid.si_opaque.so_clid.cl_id = nn->s2s_cp_cl_id;
-	stid->cs_type = cs_type;
 
 	idr_preload(GFP_KERNEL);
 	spin_lock(&nn->s2s_cp_lock);
@@ -986,6 +985,7 @@ static int nfs4_init_cp_state(struct nfsd_net *nn, copy_stateid_t *stid,
 	idr_preload_end();
 	if (new_id < 0)
 		return 0;
+	stid->cs_type = cs_type;
 	return 1;
 }
 
@@ -1019,7 +1019,8 @@ void nfs4_free_copy_state(struct nfsd4_copy *copy)
 {
 	struct nfsd_net *nn;
 
-	WARN_ON_ONCE(copy->cp_stateid.cs_type != NFS4_COPY_STID);
+	if (copy->cp_stateid.cs_type != NFS4_COPY_STID)
+		return;
 	nn = net_generic(copy->cp_clp->net, nfsd_net_id);
 	spin_lock(&nn->s2s_cp_lock);
 	idr_remove(&nn->s2s_cp_stateids,