Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        kasan-dev@googlegroups.com, Kees Cook <keescook@chromium.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 150/779] kasan: test: Silence GCC 12 warnings
Date:   Mon, 15 Aug 2022 19:56:34 +0200
Message-Id: <20220815180343.721810104@linuxfoundation.org>
In-Reply-To: <20220815180337.130757997@linuxfoundation.org>
References: <20220815180337.130757997@linuxfoundation.org>
User-Agent: quilt/0.67
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Kees Cook <keescook@chromium.org>

[ Upstream commit aaf50b1969d7933a51ea421b11432a7fb90974e3 ]

GCC 12 continues to get smarter about array accesses. The KASAN tests
are expecting to explicitly test out-of-bounds conditions at run-time,
so hide the variable from GCC, to avoid warnings like:

../lib/test_kasan.c: In function 'ksize_uaf':
../lib/test_kasan.c:790:61: warning: array subscript 120 is outside array bounds of 'void[120]' [-Warray-bounds]
  790 |         KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
      |                                       ~~~~~~~~~~~~~~~~~~~~~~^~~~~~
../lib/test_kasan.c:97:9: note: in definition of macro 'KUNIT_EXPECT_KASAN_FAIL'
   97 |         expression; \
      |         ^~~~~~~~~~

Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: kasan-dev@googlegroups.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220608214024.1068451-1-keescook@chromium.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 lib/test_kasan.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 8835e0784578..89f444cabd4a 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -125,6 +125,7 @@ static void kmalloc_oob_right(struct kunit *test)
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	/*
 	 * An unaligned access past the requested kmalloc size.
 	 * Only generic KASAN can precisely detect these.
@@ -153,6 +154,7 @@ static void kmalloc_oob_left(struct kunit *test)
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, *ptr = *(ptr - 1));
 	kfree(ptr);
 }
@@ -165,6 +167,7 @@ static void kmalloc_node_oob_right(struct kunit *test)
 	ptr = kmalloc_node(size, GFP_KERNEL, 0);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] = ptr[size]);
 	kfree(ptr);
 }
@@ -185,6 +188,7 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test)
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + OOB_TAG_OFF] = 0);
 
 	kfree(ptr);
@@ -265,6 +269,7 @@ static void kmalloc_large_oob_right(struct kunit *test)
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 0);
 	kfree(ptr);
 }
@@ -404,6 +409,8 @@ static void kmalloc_oob_16(struct kunit *test)
 	ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
 
+	OPTIMIZER_HIDE_VAR(ptr1);
+	OPTIMIZER_HIDE_VAR(ptr2);
 	KUNIT_EXPECT_KASAN_FAIL(test, *ptr1 = *ptr2);
 	kfree(ptr1);
 	kfree(ptr2);
@@ -712,6 +719,8 @@ static void ksize_unpoisons_memory(struct kunit *test)
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 	real_size = ksize(ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
+
 	/* This access shouldn't trigger a KASAN report. */
 	ptr[size] = 'x';
 
@@ -734,6 +743,7 @@ static void ksize_uaf(struct kunit *test)
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 	kfree(ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, ksize(ptr));
 	KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[0]);
 	KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
-- 
2.35.1