Prevent crash on division by zero

Currently, attempting to divide by zero in an integer expression in a dts
file will cause dtc to crash with a division by zero (SIGFPE).

This patch corrects this to properly detect this case and raise an error.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

dtc-parser.y

@@ -410,7 +410,15 @@ integer_add:
 
 integer_mul:
 	  integer_mul '*' integer_unary { $$ = $1 * $3; }
-	| integer_mul '/' integer_unary { $$ = $1 / $3; }
+	| integer_mul '/' integer_unary
+		{
+			if ($3 != 0) {
+				$$ = $1 / $3;
+			} else {
+				ERROR(&@$, "Division by zero");
+				$$ = 0;
+			}
+		}
 	| integer_mul '%' integer_unary { $$ = $1 % $3; }
 	| integer_unary
 	;

tests/division-by-zero.dts

@@ -0,0 +1,5 @@
+/dts-v1/;
+
+/ {
+	prop = < (1/0) >;
+};

tests/run_tests.sh

@@ -289,6 +289,8 @@ libfdt_tests () {
     run_test dtbs_equal_ordered embedded_nul.test.dtb embedded_nul_equiv.test.dtb
 
     run_dtc_test -I dts -O dtb bad-size-cells.dts
+
+    run_wrap_error_test $DTC division-by-zero.dts
 }
 
 dtc_tests () {