lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-Id: <20211117110916.97944-1-elver@google.com>
Date:   Wed, 17 Nov 2021 12:09:16 +0100
From:   Marco Elver <elver@...gle.com>
To:     elver@...gle.com, Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Kaiwan N Billimoria <kaiwan.billimoria@...il.com>
Subject: [PATCH] kasan: test: add globals left-out-of-bounds test

Add a test checking that KASAN generic can also detect out-of-bounds
accesses to the left of globals.

Unfortunately it seems that GCC doesn't catch this (tested GCC 10, 11).
The main difference between GCC's globals redzoning and Clang's is that
GCC relies on using increased alignment to producing padding, where
Clang's redzoning implementation actually adds real data after the
global and doesn't rely on alignment to produce padding. I believe this
is the main reason why GCC can't reliably catch globals out-of-bounds in
this case.

Given this is now a known issue, to avoid failing the whole test suite,
skip this test case with GCC.

Reported-by: Kaiwan N Billimoria <kaiwan.billimoria@...il.com>
Signed-off-by: Marco Elver <elver@...gle.com>
---
 lib/test_kasan.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 67ed689a0b1b..69c32c91420b 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -700,7 +700,7 @@ static void kmem_cache_bulk(struct kunit *test)
 
 static char global_array[10];
 
-static void kasan_global_oob(struct kunit *test)
+static void kasan_global_oob_right(struct kunit *test)
 {
 	/*
 	 * Deliberate out-of-bounds access. To prevent CONFIG_UBSAN_LOCAL_BOUNDS
@@ -723,6 +723,19 @@ static void kasan_global_oob(struct kunit *test)
 	KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)p);
 }
 
+static void kasan_global_oob_left(struct kunit *test)
+{
+	char *volatile array = global_array;
+	char *p = array - 3;
+
+	/*
+	 * GCC is known to fail this test, skip it.
+	 */
+	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_CC_IS_CLANG);
+	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC);
+	KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)p);
+}
+
 /* Check that ksize() makes the whole object accessible. */
 static void ksize_unpoisons_memory(struct kunit *test)
 {
@@ -1160,7 +1173,8 @@ static struct kunit_case kasan_kunit_test_cases[] = {
 	KUNIT_CASE(kmem_cache_oob),
 	KUNIT_CASE(kmem_cache_accounted),
 	KUNIT_CASE(kmem_cache_bulk),
-	KUNIT_CASE(kasan_global_oob),
+	KUNIT_CASE(kasan_global_oob_right),
+	KUNIT_CASE(kasan_global_oob_left),
 	KUNIT_CASE(kasan_stack_oob),
 	KUNIT_CASE(kasan_alloca_oob_left),
 	KUNIT_CASE(kasan_alloca_oob_right),
-- 
2.34.0.rc2.393.gf8c9666880-goog

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ