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Subject: Re: [PATCH v8 2/2] fs: ext4: Modify inode-test.c to use KUnit
 parameterized testing feature
To:     Marco Elver <elver@google.com>
Cc:     Brendan Higgins <brendanhiggins@google.com>,
        Shuah Khan <skhan@linuxfoundation.org>,
        Iurii Zaikin <yzaikin@google.com>,
        Theodore Ts'o <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Tim Bird <Tim.Bird@sony.com>, David Gow <davidgow@google.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        KUnit Development <kunit-dev@googlegroups.com>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-kernel-mentees@lists.linuxfoundation.org,
        linux-ext4@vger.kernel.org
References: <20201115185759.169279-1-98.arpi@gmail.com>
 <20201115185905.169349-1-98.arpi@gmail.com>
 <CANpmjNPKfPeiXUUPwz1aU6iKwOXpSZNV5ZJq22NkZZWEhE9r1w@mail.gmail.com>
From:   Arpitha Raghunandan <98.arpi@gmail.com>
Message-ID: <989852ba-2fb3-7570-ce79-a0db6cc7e99e@gmail.com>
Date:   Mon, 16 Nov 2020 10:24:53 +0530
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On 16/11/20 1:14 am, Marco Elver wrote:
> On Sun, 15 Nov 2020 at 19:59, Arpitha Raghunandan <98.arpi@gmail.com> wrote:
>>
>> Modify fs/ext4/inode-test.c to use the parameterized testing
>> feature of KUnit.
>>
>> Signed-off-by: Arpitha Raghunandan <98.arpi@gmail.com>
>> Signed-off-by: Marco Elver <elver@google.com>
>> ---
>> Changes v7->v8:
>> - Replace strcpy() with strncpy() in timestamp_expectation_to_desc()
>> Changes v6->v7:
>> - Introduce timestamp_expectation_to_desc() to convert param to
>>   description.
>> Changes v5->v6:
>> - No change to this patch of the patch series
>> Changes v4->v5:
>> - No change to this patch of the patch series
>> Changes v3->v4:
>> - Modification based on latest implementation of KUnit parameterized testing
>> Changes v2->v3:
>> - Marked hardcoded test data const
>> - Modification based on latest implementation of KUnit parameterized testing
>> Changes v1->v2:
>> - Modification based on latest implementation of KUnit parameterized testing
>>
>>  fs/ext4/inode-test.c | 323 ++++++++++++++++++++++---------------------
>>  1 file changed, 167 insertions(+), 156 deletions(-)
>>
>> diff --git a/fs/ext4/inode-test.c b/fs/ext4/inode-test.c
>> index d62d802c9c12..2c0c00c45c6b 100644
>> --- a/fs/ext4/inode-test.c
>> +++ b/fs/ext4/inode-test.c
>> @@ -80,6 +80,148 @@ struct timestamp_expectation {
>>         bool lower_bound;
>>  };
>>
>> +static const struct timestamp_expectation test_data[] = {
>> +       {
>> +               .test_case_name = LOWER_BOUND_NEG_NO_EXTRA_BITS_CASE,
>> +               .msb_set = true,
>> +               .lower_bound = true,
>> +               .extra_bits = 0,
>> +               .expected = {.tv_sec = -0x80000000LL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = UPPER_BOUND_NEG_NO_EXTRA_BITS_CASE,
>> +               .msb_set = true,
>> +               .lower_bound = false,
>> +               .extra_bits = 0,
>> +               .expected = {.tv_sec = -1LL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = LOWER_BOUND_NONNEG_NO_EXTRA_BITS_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = true,
>> +               .extra_bits = 0,
>> +               .expected = {0LL, 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = UPPER_BOUND_NONNEG_NO_EXTRA_BITS_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = false,
>> +               .extra_bits = 0,
>> +               .expected = {.tv_sec = 0x7fffffffLL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = LOWER_BOUND_NEG_LO_1_CASE,
>> +               .msb_set = true,
>> +               .lower_bound = true,
>> +               .extra_bits = 1,
>> +               .expected = {.tv_sec = 0x80000000LL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = UPPER_BOUND_NEG_LO_1_CASE,
>> +               .msb_set = true,
>> +               .lower_bound = false,
>> +               .extra_bits = 1,
>> +               .expected = {.tv_sec = 0xffffffffLL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = LOWER_BOUND_NONNEG_LO_1_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = true,
>> +               .extra_bits = 1,
>> +               .expected = {.tv_sec = 0x100000000LL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = UPPER_BOUND_NONNEG_LO_1_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = false,
>> +               .extra_bits = 1,
>> +               .expected = {.tv_sec = 0x17fffffffLL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = LOWER_BOUND_NEG_HI_1_CASE,
>> +               .msb_set = true,
>> +               .lower_bound = true,
>> +               .extra_bits =  2,
>> +               .expected = {.tv_sec = 0x180000000LL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = UPPER_BOUND_NEG_HI_1_CASE,
>> +               .msb_set = true,
>> +               .lower_bound = false,
>> +               .extra_bits = 2,
>> +               .expected = {.tv_sec = 0x1ffffffffLL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = LOWER_BOUND_NONNEG_HI_1_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = true,
>> +               .extra_bits = 2,
>> +               .expected = {.tv_sec = 0x200000000LL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = UPPER_BOUND_NONNEG_HI_1_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = false,
>> +               .extra_bits = 2,
>> +               .expected = {.tv_sec = 0x27fffffffLL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = UPPER_BOUND_NONNEG_HI_1_NS_1_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = false,
>> +               .extra_bits = 6,
>> +               .expected = {.tv_sec = 0x27fffffffLL, .tv_nsec = 1L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = LOWER_BOUND_NONNEG_HI_1_NS_MAX_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = true,
>> +               .extra_bits = 0xFFFFFFFF,
>> +               .expected = {.tv_sec = 0x300000000LL,
>> +                            .tv_nsec = MAX_NANOSECONDS},
>> +       },
>> +
>> +       {
>> +               .test_case_name = LOWER_BOUND_NONNEG_EXTRA_BITS_1_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = true,
>> +               .extra_bits = 3,
>> +               .expected = {.tv_sec = 0x300000000LL, .tv_nsec = 0L},
>> +       },
>> +
>> +       {
>> +               .test_case_name = UPPER_BOUND_NONNEG_EXTRA_BITS_1_CASE,
>> +               .msb_set = false,
>> +               .lower_bound = false,
>> +               .extra_bits = 3,
>> +               .expected = {.tv_sec = 0x37fffffffLL, .tv_nsec = 0L},
>> +       }
>> +};
>> +
>> +static void timestamp_expectation_to_desc(const struct timestamp_expectation *t,
>> +                                         char *desc)
>> +{
>> +       int desc_length = strlen(t->test_case_name);
>> +
>> +       strncpy(desc, t->test_case_name, desc_length);
>> +       desc[desc_length] = '\0';
>> +}
> 
> This unfortunately won't prevent out-of-bounds accesses if the
> description is longer than KUNIT_PARAM_DESC_SIZE.
> 
> With strncpy() we want to avoid copying more bytes than the
> destination buffer can hold. This can be done by simply a
> strncpy(desc, t->test_case_name, KUNIT_PARAM_DESC_SIZE). But,
> strncpy() is unsafe in certain cases, too, so the kernel introduced
> strscpy() -- see the note about strncpy() in
> Documentation/process/deprecated.rst. Also have a look at the
> documentation about str{n,l,s}cpy() in lib/string.c.
> 
> So, finally, what we want here is just 1 line:
> 
>     strscpy(desc, t->test_case_name, KUNIT_PARAM_DESC_SIZE);
> 

Okay, I'll look this up and make this change for v9.

> Patch 1/2 looks fine though, so hopefully v9 will be final. :-)
> 
> Thanks,
> -- Marco
> 

Thanks!