[PATCH] Fix crash with poorly defined #size-cells

[Jack Miller <jack-jZyo8ZIaZD9AfugRpC6u6w@public.gmane.org>]

If you have a parent block with #size-cells improperly set to 0, and
then subsequently try to include a regs property in the child, dtc will
crash with SIGFPE while validating it. This patch fixes that crash,
instead printing the same invalid length warning that was causing it.

Test included.

Signed-off-by: Jack Miller <jack-jZyo8ZIaZD9AfugRpC6u6w@public.gmane.org>
---
 checks.c                 |  2 +-
 tests/bad-size-cells.dts | 12 ++++++++++++
 tests/run_tests.sh       |  2 ++
 3 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 tests/bad-size-cells.dts

diff --git a/checks.c b/checks.c
index e81a8c7..0c03ac9 100644
--- a/checks.c
+++ b/checks.c
@@ -560,7 +560,7 @@ static void check_reg_format(struct check *c, struct node *dt,
 	size_cells = node_size_cells(node->parent);
 	entrylen = (addr_cells + size_cells) * sizeof(cell_t);
 
-	if ((prop->val.len % entrylen) != 0)
+	if (!entrylen || (prop->val.len % entrylen) != 0)
 		FAIL(c, "\"reg\" property in %s has invalid length (%d bytes) "
 		     "(#address-cells == %d, #size-cells == %d)",
 		     node->fullpath, prop->val.len, addr_cells, size_cells);
diff --git a/tests/bad-size-cells.dts b/tests/bad-size-cells.dts
new file mode 100644
index 0000000..515c0cc
--- /dev/null
+++ b/tests/bad-size-cells.dts
@@ -0,0 +1,12 @@
+/dts-v1/;
+
+/ {
+	mangled {
+		#address-cells = <0x0>;
+		#size-cells = <0x0>;
+
+		valid {
+            reg = <0x0 0x4000000>;
+        };
+    };
+};
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index 5331856..c870432 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -279,6 +279,8 @@ libfdt_tests () {
     run_dtc_test -I dts -O dtb -o embedded_nul.test.dtb embedded_nul.dts
     run_dtc_test -I dts -O dtb -o embedded_nul_equiv.test.dtb embedded_nul_equiv.dts
     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
 }
 
 dtc_tests () {
-- 
2.3.6