PR fortran/95530, PR fortran/95537 - Buffer overflows with long symbols

The testcases for PR95090 and PR95106 trigger buffer overflows with long
symbols that were found with an instrumented compiler.  Enlarge the
affected buffers, and add checks that the buffers will suffice.

2020-06-05  Harald Anlauf  <anlauf@gmx.de>

gcc/fortran/
	PR fortran/95530
	PR fortran/95537
	* decl.c (gfc_match_decl_type_spec): Enlarge buffer, and enhance
	string copy to detect buffer overflow.
	* gfortran.h (gfc_common_head): Enlarge buffer.
	* trans-common.c (finish_equivalences): Enhance string copy to
	detect buffer overflow.

(cherry picked from commit bcd96c9cce962ca5b2c6f8459597fb759f945ccf)

gcc/fortran/decl.c

@@ -4079,7 +4079,8 @@ match_byte_typespec (gfc_typespec *ts)
 match
 gfc_match_decl_type_spec (gfc_typespec *ts, int implicit_flag)
 {
-  char name[GFC_MAX_SYMBOL_LEN + 1];
+  /* Provide sufficient space to hold "pdtsymbol".  */
+  char name[GFC_MAX_SYMBOL_LEN + 1 + 3];
   gfc_symbol *sym, *dt_sym;
   match m;
   char c;
@@ -4269,7 +4270,11 @@ gfc_match_decl_type_spec (gfc_typespec *ts, int implicit_flag)
 	    return m;
 	  gcc_assert (!sym->attr.pdt_template && sym->attr.pdt_type);
 	  ts->u.derived = sym;
-	  strcpy (name, gfc_dt_lower_string (sym->name));
+	  const char* lower = gfc_dt_lower_string (sym->name);
+	  size_t len = strnlen (lower, sizeof (name));
+	  gcc_assert (len < sizeof (name));
+	  memcpy (name, lower, len);
+	  name[len] = '\0';
 	}
 
       if (sym && sym->attr.flavor == FL_STRUCT)

gcc/fortran/gfortran.h

@@ -1677,7 +1677,8 @@ typedef struct gfc_common_head
   char use_assoc, saved, threadprivate;
   unsigned char omp_declare_target : 1;
   unsigned char omp_declare_target_link : 1;
-  char name[GFC_MAX_SYMBOL_LEN + 1];
+  /* Provide sufficient space to hold "symbol.eq.1234567890".  */
+  char name[GFC_MAX_SYMBOL_LEN + 1 + 14];
   struct gfc_symbol *head;
   const char* binding_label;
   int is_bind_c;

gcc/fortran/trans-common.c

@@ -1313,7 +1313,11 @@ finish_equivalences (gfc_namespace *ns)
 	      c->where = ns->proc_name->declared_at;
 	    else if (ns->is_block_data)
 	      c->where = ns->sym_root->n.sym->declared_at;
-	    strcpy (c->name, z->module);
+
+	    size_t len = strlen (z->module);
+	    gcc_assert (len < sizeof (c->name));
+	    memcpy (c->name, z->module, len);
+	    c->name[len] = '\0';
 	  }
 	else
 	  c = NULL;