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, 1 insertions, 1 deletions

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 400a71e75238..cfef738d765e 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -281,7 +281,7 @@ struct rpc_clnt *nfs4_negotiate_security(struct rpc_clnt *, struct inode *,
 int nfs4_submount(struct fs_context *, struct nfs_server *);
 int nfs4_replace_transport(struct nfs_server *server,
 				const struct nfs4_fs_locations *locations);
-size_t nfs_parse_server_name(char *string, size_t len, struct sockaddr *sa,
+size_t nfs_parse_server_name(char *string, size_t len, struct sockaddr_storage *ss,
 			     size_t salen, struct net *net, int port);
 /* nfs4proc.c */
 extern int nfs4_handle_exception(struct nfs_server *, int, struct nfs4_exception *);