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Date:   Thu, 13 Jun 2019 14:30:26 +0200
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Subject: [PATCH v4 1/3] lib/test_kasan: Add bitops tests
From:   Marco Elver <elver@google.com>
To:     peterz@infradead.org, aryabinin@virtuozzo.com, dvyukov@google.com,
        glider@google.com, andreyknvl@google.com, mark.rutland@arm.com,
        hpa@zytor.com
Cc:     corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        x86@kernel.org, arnd@arndb.de, jpoimboe@redhat.com,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arch@vger.kernel.org, kasan-dev@googlegroups.com,
        Marco Elver <elver@google.com>
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Sender: linux-kernel-owner@vger.kernel.org
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This adds bitops tests to the test_kasan module. In a follow-up patch,
support for bitops instrumentation will be added.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
---
Changes in v4:
* Remove "within-bounds" tests.
* Allocate sizeof(*bite) + 1, to not actually corrupt other memory in
  case instrumentation isn't working.
* Clarify that accesses operate on whole longs, which causes OOB
  regardless of the bit accessed beyond the first long in the test.

Changes in v3:
* Use kzalloc instead of kmalloc.
* Use sizeof(*bits).

Changes in v2:
* Use BITS_PER_LONG.
* Use heap allocated memory for test, as newer compilers (correctly)
  warn on OOB stack access.
---
 lib/test_kasan.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 79 insertions(+), 3 deletions(-)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 7de2702621dc..e76a4711d456 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -11,16 +11,17 @@
 
 #define pr_fmt(fmt) "kasan test: %s " fmt, __func__
 
+#include <linux/bitops.h>
 #include <linux/delay.h>
+#include <linux/kasan.h>
 #include <linux/kernel.h>
-#include <linux/mman.h>
 #include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/module.h>
 #include <linux/printk.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/uaccess.h>
-#include <linux/module.h>
-#include <linux/kasan.h>
 
 /*
  * Note: test functions are marked noinline so that their names appear in
@@ -623,6 +624,80 @@ static noinline void __init kasan_strings(void)
 	strnlen(ptr, 1);
 }
 
+static noinline void __init kasan_bitops(void)
+{
+	/*
+	 * Allocate 1 more byte, which causes kzalloc to round up to 16-bytes;
+	 * this way we do not actually corrupt other memory, in case
+	 * instrumentation is not working as intended.
+	 */
+	long *bits = kzalloc(sizeof(*bits) + 1, GFP_KERNEL);
+	if (!bits)
+		return;
+
+	/*
+	 * Below calls try to access bit within allocated memory; however, the
+	 * below accesses are still out-of-bounds, since bitops are defined to
+	 * operate on the whole long the bit is in.
+	 */
+	pr_info("out-of-bounds in set_bit\n");
+	set_bit(BITS_PER_LONG, bits);
+
+	pr_info("out-of-bounds in __set_bit\n");
+	__set_bit(BITS_PER_LONG, bits);
+
+	pr_info("out-of-bounds in clear_bit\n");
+	clear_bit(BITS_PER_LONG, bits);
+
+	pr_info("out-of-bounds in __clear_bit\n");
+	__clear_bit(BITS_PER_LONG, bits);
+
+	pr_info("out-of-bounds in clear_bit_unlock\n");
+	clear_bit_unlock(BITS_PER_LONG, bits);
+
+	pr_info("out-of-bounds in __clear_bit_unlock\n");
+	__clear_bit_unlock(BITS_PER_LONG, bits);
+
+	pr_info("out-of-bounds in change_bit\n");
+	change_bit(BITS_PER_LONG, bits);
+
+	pr_info("out-of-bounds in __change_bit\n");
+	__change_bit(BITS_PER_LONG, bits);
+
+	/*
+	 * Below calls try to access bit beyond allocated memory.
+	 */
+	pr_info("out-of-bounds in test_and_set_bit\n");
+	test_and_set_bit(BITS_PER_LONG + BITS_PER_BYTE, bits);
+
+	pr_info("out-of-bounds in __test_and_set_bit\n");
+	__test_and_set_bit(BITS_PER_LONG + BITS_PER_BYTE, bits);
+
+	pr_info("out-of-bounds in test_and_set_bit_lock\n");
+	test_and_set_bit_lock(BITS_PER_LONG + BITS_PER_BYTE, bits);
+
+	pr_info("out-of-bounds in test_and_clear_bit\n");
+	test_and_clear_bit(BITS_PER_LONG + BITS_PER_BYTE, bits);
+
+	pr_info("out-of-bounds in __test_and_clear_bit\n");
+	__test_and_clear_bit(BITS_PER_LONG + BITS_PER_BYTE, bits);
+
+	pr_info("out-of-bounds in test_and_change_bit\n");
+	test_and_change_bit(BITS_PER_LONG + BITS_PER_BYTE, bits);
+
+	pr_info("out-of-bounds in __test_and_change_bit\n");
+	__test_and_change_bit(BITS_PER_LONG + BITS_PER_BYTE, bits);
+
+	pr_info("out-of-bounds in test_bit\n");
+	(void)test_bit(BITS_PER_LONG + BITS_PER_BYTE, bits);
+
+#if defined(clear_bit_unlock_is_negative_byte)
+	pr_info("out-of-bounds in clear_bit_unlock_is_negative_byte\n");
+	clear_bit_unlock_is_negative_byte(BITS_PER_LONG + BITS_PER_BYTE, bits);
+#endif
+	kfree(bits);
+}
+
 static int __init kmalloc_tests_init(void)
 {
 	/*
@@ -664,6 +739,7 @@ static int __init kmalloc_tests_init(void)
 	kasan_memchr();
 	kasan_memcmp();
 	kasan_strings();
+	kasan_bitops();
 
 	kasan_restore_multi_shot(multishot);
 
-- 
2.22.0.rc2.383.gf4fbbf30c2-goog