On Tue, Feb 10 2015, Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>> >> ---
>> >> index ab0d30e1e18f..5f759c3c2f60 100644
>> >> --- a/lib/test-string_helpers.c
>> >> +++ b/lib/test-string_helpers.c
>> >> @@ -264,12 +264,12 @@ static __init void test_string_escape(const char *name,
>> >> const struct test_string_2 *s2,
>> >> unsigned int flags, const char *esc)
>> >> {
>> >> - int q_real = 512;
>> >> - char *out_test = kmalloc(q_real, GFP_KERNEL);
>> >> - char *out_real = kmalloc(q_real, GFP_KERNEL);
>> >> + size_t out_size = 512;
>> >> + char *out_test = kmalloc(out_size, GFP_KERNEL);
>> >> + char *out_real = kmalloc(out_size, GFP_KERNEL);
>> >> char *in = kmalloc(256, GFP_KERNEL);
>> >> - char *buf = out_real;
>> >> int p = 0, q_test = 0;
>> >> + int q_real;
>> >>
>> >> if (!out_test || !out_real || !in)
>> >> goto out;
>> >> @@ -301,29 +301,26 @@ static __init void test_string_escape(const char *name,
>> >> q_test += len;
>> >> }
>> >>
>> >> - q_real = string_escape_mem(in, p, &buf, q_real, flags, esc);
>> >> + q_real = string_escape_mem(in, p, out_real, out_size, flags, esc);
>> >>
>> >> test_string_check_buf(name, flags, in, p, out_real, q_real, out_test,
>> >> q_test);
>> >> +
>> >> + memset(out_real, 'Z', out_size);
>> >> + q_real = string_escape_mem(in, p, out_real, 0, flags, esc);
>> >> + if (q_real != q_test)
>> >> + pr_warn("Test '%s' failed: flags = %u, osz = 0, expected %d, got %d\n",
>> >> + name, flags, q_test, q_real);
>> >> + if (memchr_inv(out_real, 'Z', out_size))
>> >> + pr_warn("Test '%s' failed: osz = 0 but string_escape_mem wrote to the buffer\n",
>> >> + name);
>> >> +
>> >
>> > So, why couldn't we split this to separate test case? It seems I already
>> > pointed this out.
>> >
>>
>> This actually provides better coverage
>
> I do not see much advantage of doing so. You may create a loop with
> random number for in-size and check. So, I prefer to see separate case
> for that.
It's not about the size, it's about exercising all the various escape_*
helpers, to ensure that they all respect the end of the buffer, while
still returning the correct would-be output size. For that, one needs to
call string_escape_mem with various combinations of flags and input
buffers. The logic for that is already in place in test_string_escape
and its caller, and I see no point in duplicating all that.
If you insist on a separate function for doing the overflow testing,
I'll just rip it out from my code and let you add such a test later.
I've updated 2/3 with the early returns you suggested, but I'll wait a
little before sending out a v4.
Rasmus
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