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From: Marco Elver <elver@google.com>
Date: Mon, 5 Feb 2024 12:07:20 +0100
Message-ID: <CANpmjNNMJn7xtpUxwxiUV1KXgMsDmyvGAq+4etFy5aiESdcDxg@mail.gmail.com>
Subject: Re: [PATCH v2] ubsan: Silence W=1 warnings in self-test
To: Kees Cook <keescook@chromium.org>
Cc: kernel test robot <lkp@intel.com>, Andrey Konovalov <andreyknvl@gmail.com>, linux-kernel@vger.kernel.org, 
	kasan-dev@googlegroups.com, linux-hardening@vger.kernel.org
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On Mon, 5 Feb 2024 at 10:03, Kees Cook <keescook@chromium.org> wrote:
>
> Silence a handful of W=1 warnings in the UBSan selftest, which set
> variables without using them. For example:
>
>    lib/test_ubsan.c:101:6: warning: variable 'val1' set but not used [-Wunused-but-set-variable]
>      101 |         int val1 = 10;
>          |             ^
>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202401310423.XpCIk6KO-lkp@intel.com/
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Marco Elver <elver@google.com>

> ---
> v2:
>  - add additional "volatile" annotations for potential future proofing (marco)
> v1: https://lore.kernel.org/all/20240202094550.work.205-kees@kernel.org/
> ---
>  lib/Makefile     | 1 +
>  lib/test_ubsan.c | 4 ++--
>  2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/lib/Makefile b/lib/Makefile
> index 6b09731d8e61..bc36a5c167db 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -69,6 +69,7 @@ obj-$(CONFIG_HASH_KUNIT_TEST) += test_hash.o
>  obj-$(CONFIG_TEST_IDA) += test_ida.o
>  obj-$(CONFIG_TEST_UBSAN) += test_ubsan.o
>  CFLAGS_test_ubsan.o += $(call cc-disable-warning, vla)
> +CFLAGS_test_ubsan.o += $(call cc-disable-warning, unused-but-set-variable)
>  UBSAN_SANITIZE_test_ubsan.o := y
>  obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
>  obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
> diff --git a/lib/test_ubsan.c b/lib/test_ubsan.c
> index 2062be1f2e80..f4ee2484d4b5 100644
> --- a/lib/test_ubsan.c
> +++ b/lib/test_ubsan.c
> @@ -23,8 +23,8 @@ static void test_ubsan_divrem_overflow(void)
>  static void test_ubsan_shift_out_of_bounds(void)
>  {
>         volatile int neg = -1, wrap = 4;
> -       int val1 = 10;
> -       int val2 = INT_MAX;
> +       volatile int val1 = 10;
> +       volatile int val2 = INT_MAX;
>
>         UBSAN_TEST(CONFIG_UBSAN_SHIFT, "negative exponent");
>         val1 <<= neg;
> --
> 2.34.1
>
> --
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