NFS: Avoid memcpy() run-time warning for struct sockaddr overflows

The 'nfs_server' and 'mount_server' structures include a union of
'struct sockaddr' (with the older 16 bytes max address size) and
'struct sockaddr_storage' which is large enough to hold all the
supported sa_family types (128 bytes max size). The runtime memcpy()
buffer overflow checker is seeing attempts to write beyond the 16
bytes as an overflow, but the actual expected size is that of 'struct
sockaddr_storage'. Plumb the use of 'struct sockaddr_storage' more
completely through-out NFS, which results in adjusting the memcpy()
buffers to the correct union members. Avoids this false positive run-time
warning under CONFIG_FORTIFY_SOURCE:

  memcpy: detected field-spanning write (size 28) of single field "&ctx->nfs_server.address" at fs/nfs/namespace.c:178 (size 16)

Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/all/202210110948.26b43120-yujie.liu@intel.com
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Anna Schumaker <anna@kernel.org>
Cc: linux-nfs@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 9 insertions, 9 deletions

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 7a5162afa5c0..3b9b53481309 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -889,7 +889,7 @@ nfs4_find_client_sessionid(struct net *net, const struct sockaddr *addr,
  */
 static int nfs4_set_client(struct nfs_server *server,
 		const char *hostname,
-		const struct sockaddr *addr,
+		const struct sockaddr_storage *addr,
 		const size_t addrlen,
 		const char *ip_addr,
 		int proto, const struct rpc_timeout *timeparms,
@@ -924,7 +924,7 @@ static int nfs4_set_client(struct nfs_server *server,
 		__set_bit(NFS_CS_MIGRATION, &cl_init.init_flags);
 	if (test_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status))
 		__set_bit(NFS_CS_TSM_POSSIBLE, &cl_init.init_flags);
-	server->port = rpc_get_port(addr);
+	server->port = rpc_get_port((struct sockaddr *)addr);
 
 	/* Allocate or find a client reference we can use */
 	clp = nfs_get_client(&cl_init);
@@ -960,7 +960,7 @@ static int nfs4_set_client(struct nfs_server *server,
  * the MDS.
  */
 struct nfs_client *nfs4_set_ds_client(struct nfs_server *mds_srv,
-		const struct sockaddr *ds_addr, int ds_addrlen,
+		const struct sockaddr_storage *ds_addr, int ds_addrlen,
 		int ds_proto, unsigned int ds_timeo, unsigned int ds_retrans,
 		u32 minor_version)
 {
@@ -980,7 +980,7 @@ struct nfs_client *nfs4_set_ds_client(struct nfs_server *mds_srv,
 	};
 	char buf[INET6_ADDRSTRLEN + 1];
 
-	if (rpc_ntop(ds_addr, buf, sizeof(buf)) <= 0)
+	if (rpc_ntop((struct sockaddr *)ds_addr, buf, sizeof(buf)) <= 0)
 		return ERR_PTR(-EINVAL);
 	cl_init.hostname = buf;
 
@@ -1148,7 +1148,7 @@ static int nfs4_init_server(struct nfs_server *server, struct fs_context *fc)
 	/* Get a client record */
 	error = nfs4_set_client(server,
 				ctx->nfs_server.hostname,
-				&ctx->nfs_server.address,
+				&ctx->nfs_server._address,
 				ctx->nfs_server.addrlen,
 				ctx->client_address,
 				ctx->nfs_server.protocol,
@@ -1238,7 +1238,7 @@ struct nfs_server *nfs4_create_referral_server(struct fs_context *fc)
 	rpc_set_port(&ctx->nfs_server.address, NFS_RDMA_PORT);
 	error = nfs4_set_client(server,
 				ctx->nfs_server.hostname,
-				&ctx->nfs_server.address,
+				&ctx->nfs_server._address,
 				ctx->nfs_server.addrlen,
 				parent_client->cl_ipaddr,
 				XPRT_TRANSPORT_RDMA,
@@ -1254,7 +1254,7 @@ struct nfs_server *nfs4_create_referral_server(struct fs_context *fc)
 	rpc_set_port(&ctx->nfs_server.address, NFS_PORT);
 	error = nfs4_set_client(server,
 				ctx->nfs_server.hostname,
-				&ctx->nfs_server.address,
+				&ctx->nfs_server._address,
 				ctx->nfs_server.addrlen,
 				parent_client->cl_ipaddr,
 				XPRT_TRANSPORT_TCP,
@@ -1303,14 +1303,14 @@ error:
  * Returns zero on success, or a negative errno value.
  */
 int nfs4_update_server(struct nfs_server *server, const char *hostname,
-		       struct sockaddr *sap, size_t salen, struct net *net)
+		       struct sockaddr_storage *sap, size_t salen, struct net *net)
 {
 	struct nfs_client *clp = server->nfs_client;
 	struct rpc_clnt *clnt = server->client;
 	struct xprt_create xargs = {
 		.ident		= clp->cl_proto,
 		.net		= net,
-		.dstaddr	= sap,
+		.dstaddr	= (struct sockaddr *)sap,
 		.addrlen	= salen,
 		.servername	= hostname,
 	};