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[PATCH] Fix -fsanitize=bounds crash with zero-size array (PR sanitizer/79558)


We crash here becase ubsan_type_descriptor isn't able to handle arrays
such as int[0:], i.e. where the TYPE_MAX_VALUE of the domain is missing.
Fixed by checking that first, which means we'd print '*' instead if it
is missing.

Bootstrapped/regtested on x86_64-linux, ok for trunk/6?

2017-02-20  Marek Polacek  <polacek@redhat.com>

	PR sanitizer/79558
	* ubsan.c (ubsan_type_descriptor): Check if TYPE_MAX_VALUE is null.

	* c-c++-common/ubsan/bounds-14.c: New test.

diff --git gcc/testsuite/c-c++-common/ubsan/bounds-14.c gcc/testsuite/c-c++-common/ubsan/bounds-14.c
index e69de29..ddb5251 100644
--- gcc/testsuite/c-c++-common/ubsan/bounds-14.c
+++ gcc/testsuite/c-c++-common/ubsan/bounds-14.c
@@ -0,0 +1,13 @@
+/* PR sanitizer/79558 */
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=bounds" } */
+
+void
+fn1 (int n)
+{
+  int i, j;
+  int x[2][0];
+  for (i = 0; i < n; i++)
+    for (j = 0; j < n; j++)
+      x[i][j] = 5;
+}
diff --git gcc/ubsan.c gcc/ubsan.c
index 0291401..11a41e1 100644
--- gcc/ubsan.c
+++ gcc/ubsan.c
@@ -409,7 +409,9 @@ ubsan_type_descriptor (tree type, enum ubsan_print_style pstyle)
 	{
 	  pp_left_bracket (&pretty_name);
 	  tree dom = TYPE_DOMAIN (t);
-	  if (dom && TREE_CODE (TYPE_MAX_VALUE (dom)) == INTEGER_CST)
+	  if (dom != NULL_TREE
+	      && TYPE_MAX_VALUE (dom) != NULL_TREE
+	      && TREE_CODE (TYPE_MAX_VALUE (dom)) == INTEGER_CST)
 	    {
 	      if (tree_fits_uhwi_p (TYPE_MAX_VALUE (dom))
 		  && tree_to_uhwi (TYPE_MAX_VALUE (dom)) + 1 != 0)

	Marek


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