Re: [PATCH v2 1/3] lib/test_kasan: Add bitops tests

Mark Rutland
2019-05-29T15:15:15Z

On Wed, May 29, 2019 at 04:14:59PM +0200, Marco Elver wrote:
> 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>
> ---
> 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 | 75 ++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 72 insertions(+), 3 deletions(-)
>
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index 7de2702621dc..6562df0ca30d 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 +624,73 @@ static noinline void __init kasan_strings(void)
> strnlen(ptr, 1);
> }
>
> +static noinline void __init kasan_bitops(void)
> +{
> + long *bits = kmalloc(sizeof(long), GFP_KERNEL | __GFP_ZERO);

Trivial nit, but this can/should be:

long *bits = kzalloc(sizeof(*bits), GFP_KERNEL);

... which is the usual style for sizeof() to keep the LHS and RHS types
the same, and using kzalloc avoids the need to explicitly pass
__GFP_ZERO.

Otherwise, this looks good to me.

> + if (!bits)
> + return;
> +
> + pr_info("within-bounds in set_bit");
> + set_bit(0, bits);
> +
> + pr_info("within-bounds in set_bit");
> + set_bit(BITS_PER_LONG - 1, bits);
> +
> + 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);
> +
> + pr_info("out-of-bounds in test_and_set_bit\n");
> + test_and_set_bit(BITS_PER_LONG, bits);
> +
> + pr_info("out-of-bounds in __test_and_set_bit\n");
> + __test_and_set_bit(BITS_PER_LONG, bits);
> +
> + pr_info("out-of-bounds in test_and_set_bit_lock\n");
> + test_and_set_bit_lock(BITS_PER_LONG, bits);
> +
> + pr_info("out-of-bounds in test_and_clear_bit\n");
> + test_and_clear_bit(BITS_PER_LONG, bits);
> +
> + pr_info("out-of-bounds in __test_and_clear_bit\n");
> + __test_and_clear_bit(BITS_PER_LONG, bits);
> +
> + pr_info("out-of-bounds in test_and_change_bit\n");
> + test_and_change_bit(BITS_PER_LONG, bits);
> +
> + pr_info("out-of-bounds in __test_and_change_bit\n");
> + __test_and_change_bit(BITS_PER_LONG, bits);
> +
> + pr_info("out-of-bounds in test_bit\n");
> + (void)test_bit(BITS_PER_LONG, 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);
> +#endif
> + kfree(bits);
> +}
> +
> static int __init kmalloc_tests_init(void)
> {
> /*
> @@ -664,6 +732,7 @@ static int __init kmalloc_tests_init(void)
> kasan_memchr();
> kasan_memcmp();
> kasan_strings();
> + kasan_bitops();
>
> kasan_restore_multi_shot(multishot);
>
> --
> 2.22.0.rc1.257.g3120a18244-goog
>