Fix potential array overrun in x86 assembler.

* config/tc-i386.c (parse_operands): Check for operand overflow
	before setting the unspecified bit.

gas/ChangeLog

@@ -1,3 +1,8 @@
+2017-01-20  Nick Clifton  <nickc@redhat.com>
+
+	* config/tc-i386.c (parse_operands): Check for operand overflow
+	before setting the unspecified bit.
+
 2017-01-18  Maciej W. Rozycki  <macro@imgtec.com>
 
 	PR gas/20649

gas/config/tc-i386.c

@@ -4136,13 +4136,13 @@ parse_operands (char *l, const char *mnemonic)
 	{			/* Yes, we've read in another operand.  */
 	  unsigned int operand_ok;
 	  this_operand = i.operands++;
-	  i.types[this_operand].bitfield.unspecified = 1;
 	  if (i.operands > MAX_OPERANDS)
 	    {
 	      as_bad (_("spurious operands; (%d operands/instruction max)"),
 		      MAX_OPERANDS);
 	      return NULL;
 	    }
+	  i.types[this_operand].bitfield.unspecified = 1;
 	  /* Now parse operand adding info to 'i' as we go along.  */
 	  END_STRING_AND_SAVE (l);