+ lib-tests-string_helpers-check-null-terminator-too.patch added to mm-nonmm-unstable branch

+ lib-tests-string_helpers-check-null-terminator-too.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: lib/tests: string_helpers: check null terminator too
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     lib-tests-string_helpers-check-null-terminator-too.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-tests-string_helpers-check-null-terminator-too.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Jonas Rebmann <jre@pengutronix.de>
Subject: lib/tests: string_helpers: check null terminator too
Date: Wed, 16 Sep 2026 19:38:06 +0200

Patch series "lib/string_helpers: fixes and test cases for
string_unescape()".

This series fixes two bugs in string_unescape() regarding the destination
buffer length.  Both fixes are accompanied with kunit tests which would
fail without the fixes.

To make this possible, preparatory patches 1 and 2 improve and clean up
testing helpers and 3 introduces test_unescape_one() which allows for
targeted testing of the string_unescape() function.


This patch (of 5):

string_unescape() returns the number of character written to dst, not
counting the null terminator which is always written.

Ensure string_unescape has included the null terminator by adding a
separate check.

While at it, improve output for failed tests by showing the memory dump
even if the length differs.

Link: https://lore.kernel.org/20260916-string_unescape-v1-0-7f8bd986fa33@pengutronix.de
Link: https://lore.kernel.org/20260916-string_unescape-v1-1-7f8bd986fa33@pengutronix.de
Signed-off-by: Jonas Rebmann <jre@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
---

 lib/tests/string_helpers_kunit.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/lib/tests/string_helpers_kunit.c~lib-tests-string_helpers-check-null-terminator-too
+++ a/lib/tests/string_helpers_kunit.c
@@ -22,7 +22,7 @@ static void test_string_check_buf(struct
 				  char *out_real, size_t q_real,
 				  char *out_test, size_t q_test)
 {
-	KUNIT_ASSERT_EQ_MSG(test, q_real, q_test, "name:%s", name);
+	KUNIT_EXPECT_EQ_MSG(test, q_real, q_test, "name:%s", name);
 	KUNIT_EXPECT_MEMEQ_MSG(test, out_test, out_real, q_test,
 			       "name:%s", name);
 }
@@ -103,6 +103,7 @@ static void test_string_unescape(struct
 
 	test_string_check_buf(test, name, flags, in, p - 1, out_real, q_real,
 			      out_test, q_test);
+	KUNIT_EXPECT_EQ_MSG(test, out_real[q_real], '\0', "name:%s", name);
 }
 
 struct test_string_1 {
_

Patches currently in -mm which might be from jre@pengutronix.de are

lib-tests-string_helpers-check-null-terminator-too.patch
lib-tests-string_helpers-drop-unused-parameters.patch
lib-tests-string_helpers-introduce-test_string_unescape_one.patch
lib-string_helpers-use-full-destination-buffer-in-string_unescape.patch
lib-string_helpers-fix-counting-of-remaining-bytes-in-string_unescape.patch