Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index 7510dc6..4b280fc 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -1033,13 +1033,14 @@
 				return DBG_PASS_EVENT;
 			}
 #endif
+			/* Fall through */
 		case 'C': /* Exception passing */
 			tmp = gdb_cmd_exception_pass(ks);
 			if (tmp > 0)
 				goto default_handle;
 			if (tmp == 0)
 				break;
-			/* Fall through on tmp < 0 */
+			/* Fall through - on tmp < 0 */
 		case 'c': /* Continue packet */
 		case 's': /* Single step packet */
 			if (kgdb_contthread && kgdb_contthread != current) {
@@ -1048,7 +1049,7 @@
 				break;
 			}
 			dbg_activate_sw_breakpoints();
-			/* Fall through to default processing */
+			/* Fall through - to default processing */
 		default:
 default_handle:
 			error = kgdb_arch_handle_exception(ks->ex_vector,
@@ -1094,10 +1095,10 @@
 		return error;
 	case 's':
 	case 'c':
-		strcpy(remcom_in_buffer, cmd);
+		strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
 		return 0;
 	case '$':
-		strcpy(remcom_in_buffer, cmd);
+		strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
 		gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
 		gdbstub_prev_in_buf_pos = 0;
 		return 0;