[DTrace-devel] [External] : [PATCH 2/3] test: strlen() must not overwrite the rodata or the zeros

[Eslam Almorshdy via B4 Relay]

From: Eslam Almorshdy <ealmorshdy at d-matrix.ai>

Both tests call strlen() on a string longer than strsize, then use
what it used to overwrite.  tst.no-clobber-zeros.d checks that keys
built before the call still find their elements and that a new
aggregation starts from zero.  tst.no-clobber-rodata.d checks that
inet_ntoa6(), which reads a table from the read-only data, still
formats ::1.  They are separate because when a program has read-only
data, it lies in front of the zeros and takes the whole overwrite.

Both fail without the previous patch.

Assisted-by: Claude Code:claude-opus-5-5
Signed-off-by: Eslam Almorshdy <ealmorshdy at d-matrix.ai>
---
 test/unittest/funcs/strlen/tst.no-clobber-rodata.d | 37 ++++++++++++++++++
 test/unittest/funcs/strlen/tst.no-clobber-rodata.r |  3 ++
 test/unittest/funcs/strlen/tst.no-clobber-zeros.d  | 45 ++++++++++++++++++++++
 test/unittest/funcs/strlen/tst.no-clobber-zeros.r  |  5 +++
 4 files changed, 90 insertions(+)

diff --git a/test/unittest/funcs/strlen/tst.no-clobber-rodata.d b/test/unittest/funcs/strlen/tst.no-clobber-rodata.d
new file mode 100644
index 00000000..1b452fd5
--- /dev/null
+++ b/test/unittest/funcs/strlen/tst.no-clobber-rodata.d
@@ -0,0 +1,37 @@
+/*
+ * Oracle Linux DTrace.
+ * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
+ * Licensed under the Universal Permissive License v 1.0 as shown at
+ * http://oss.oracle.com/licenses/upl.
+ */
+
+/*
+ * ASSERTION: strlen() does not overwrite the read-only data.
+ *
+ * SECTION: Actions and Subroutines/strlen()
+ */
+
+#pragma D option quiet
+#pragma D option strsize=32
+
+BEGIN
+{
+	this->ip6 = (struct in6_addr *)alloca(sizeof(struct in6_addr));
+	this->ip6->in6_u.u6_addr32[0] = 0;
+	this->ip6->in6_u.u6_addr32[1] = 0;
+	this->ip6->in6_u.u6_addr32[2] = 0;
+	this->ip6->in6_u.u6_addr32[3] = 0;
+	this->ip6->in6_u.u6_addr8[15] = 1;
+
+	/* Longer than strsize: strlen() copies as much as it can. */
+	printf("%d\n", strlen("0123456789012345678901234567890123456789"));
+
+	/* inet_ntoa6() uses a table in the read-only data. */
+	printf("%s\n", inet_ntoa6(this->ip6));
+	exit(0);
+}
+
+ERROR
+{
+	exit(1);
+}
diff --git a/test/unittest/funcs/strlen/tst.no-clobber-rodata.r b/test/unittest/funcs/strlen/tst.no-clobber-rodata.r
new file mode 100644
index 00000000..eb33a6be
--- /dev/null
+++ b/test/unittest/funcs/strlen/tst.no-clobber-rodata.r
@@ -0,0 +1,3 @@
+31
+::1
+
diff --git a/test/unittest/funcs/strlen/tst.no-clobber-zeros.d b/test/unittest/funcs/strlen/tst.no-clobber-zeros.d
new file mode 100644
index 00000000..5cd866e5
--- /dev/null
+++ b/test/unittest/funcs/strlen/tst.no-clobber-zeros.d
@@ -0,0 +1,45 @@
+/*
+ * Oracle Linux DTrace.
+ * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
+ * Licensed under the Universal Permissive License v 1.0 as shown at
+ * http://oss.oracle.com/licenses/upl.
+ */
+
+/*
+ * ASSERTION: strlen() does not overwrite the block of zeros that tuple
+ *	      keys and new aggregations are initialized from.
+ *
+ * SECTION: Actions and Subroutines/strlen()
+ */
+
+#pragma D option quiet
+#pragma D option strsize=32
+
+BEGIN
+{
+	a["k"] = 1;
+	@s["k"] = sum(1);
+
+	/* Longer than strsize: strlen() copies as much as it can. */
+	printf("%d\n", strlen("0123456789012345678901234567890123456789"));
+
+	/* The same keys must find the same elements as before. */
+	printf("%d\n", a["k"]);
+	@s["k"] = sum(1);
+
+	/* A new aggregation must start from zero. */
+	@c = count();
+
+	exit(0);
+}
+
+END
+{
+	printa("%s %@d\n", @s);
+	printa("%@d\n", @c);
+}
+
+ERROR
+{
+	exit(1);
+}
diff --git a/test/unittest/funcs/strlen/tst.no-clobber-zeros.r b/test/unittest/funcs/strlen/tst.no-clobber-zeros.r
new file mode 100644
index 00000000..68fe1b8a
--- /dev/null
+++ b/test/unittest/funcs/strlen/tst.no-clobber-zeros.r
@@ -0,0 +1,5 @@
+31
+1
+k 2
+1
+

-- 
2.55.0