genksyms: Fix segfault with invalid declarations

commit d920f7c6 upstream.

Do not try to recover too early and segfault when parsing invalid
declarations such as

echo 'int (int);' | scripts/genksyms/genksyms
echo 'int a, (int);' | scripts/genksyms/genksyms
echo 'extern void *__inline_memcpy((void *), (const void *), (__kernel_size_t));' | scripts/genksyms/genksyms

The last one was a real-life bug with
include/asm-generic/asm-prototypes.h on x86_64.
Reported-and-tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Michal Marek <mmarek@suse.com>
[arnd: rebase to 4.4, regenerate parse.tab.{c,h}]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

scripts/genksyms/parse.tab.h_shipped

-/* A Bison parser, made by GNU Bison 2.7.  */
+/* A Bison parser, made by GNU Bison 3.0.4.  */
 
 /* Bison interface for Yacc-like parsers in C
 
-      Copyright (C) 1984, 1989-1990, 2000-2012 Free Software Foundation, Inc.
+   Copyright (C) 1984, 1989-1990, 2000-2015 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -30,22 +30,21 @@
    This special exception was added by the Free Software Foundation in
    version 2.2 of Bison.  */
 
-#ifndef YY_YY_SCRIPTS_GENKSYMS_PARSE_TAB_H_SHIPPED_INCLUDED
-# define YY_YY_SCRIPTS_GENKSYMS_PARSE_TAB_H_SHIPPED_INCLUDED
-/* Enabling traces.  */
+#ifndef YY_YY_PARSE_TAB_H_INCLUDED
+# define YY_YY_PARSE_TAB_H_INCLUDED
+/* Debug traces.  */
 #ifndef YYDEBUG
-# define YYDEBUG 1
+# define YYDEBUG 0
 #endif
 #if YYDEBUG
 extern int yydebug;
 #endif
 
-/* Tokens.  */
+/* Token type.  */
 #ifndef YYTOKENTYPE
 # define YYTOKENTYPE
-   /* Put the tokens into the symbol table, so that GDB and other debuggers
-      know about them.  */
-   enum yytokentype {
+  enum yytokentype
+  {
     ASM_KEYW = 258,
     ATTRIBUTE_KEYW = 259,
     AUTO_KEYW = 260,
@@ -91,28 +90,16 @@ extern int yydebug;
   };
 #endif
 
-
+/* Value type.  */
 #if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
 typedef int YYSTYPE;
 # define YYSTYPE_IS_TRIVIAL 1
-# define yystype YYSTYPE /* obsolescent; will be withdrawn */
 # define YYSTYPE_IS_DECLARED 1
 #endif
 
+
 extern YYSTYPE yylval;
 
-#ifdef YYPARSE_PARAM
-#if defined __STDC__ || defined __cplusplus
-int yyparse (void *YYPARSE_PARAM);
-#else
-int yyparse ();
-#endif
-#else /* ! YYPARSE_PARAM */
-#if defined __STDC__ || defined __cplusplus
 int yyparse (void);
-#else
-int yyparse ();
-#endif
-#endif /* ! YYPARSE_PARAM */
 
-#endif /* !YY_YY_SCRIPTS_GENKSYMS_PARSE_TAB_H_SHIPPED_INCLUDED  */
+#endif /* !YY_YY_PARSE_TAB_H_INCLUDED  */

scripts/genksyms/parse.y

@@ -320,8 +320,6 @@ direct_declarator:
 		{ $$ = $2; }
 	| '(' declarator ')'
 		{ $$ = $3; }
-	| '(' error ')'
-		{ $$ = $3; }
 	;
 
 /* Nested declarators differ from regular declarators in that they do