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From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Trond Myklebust <trond.myklebust@primarydata.com>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	"David S. Miller" <davem@davemloft.net>,
	linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: [PATCH v3 3/3] lib/string_helpers.c: Change semantics of string_escape_mem
Date: Sat, 21 Feb 2015 02:35:45 +0100	[thread overview]
Message-ID: <87oaoo59n2.fsf@rasmusvillemoes.dk> (raw)
In-Reply-To: <1423578150.31903.480.camel@linux.intel.com> (Andy Shevchenko's message of "Tue, 10 Feb 2015 16:22:30 +0200")

On Tue, Feb 10 2015, Andy Shevchenko <andriy.shevchenko@linux.intel.com> 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

  reply	other threads:[~2015-02-21  1:35 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-28 13:25 [PATCH 0/2] Two printf fixes Rasmus Villemoes
2015-01-28 13:25 ` [PATCH 1/2] lib/vsprintf.c: Fix potential NULL deref in hex_string Rasmus Villemoes
2015-01-28 14:53   ` Andy Shevchenko
2015-01-28 15:49     ` Rasmus Villemoes
2015-01-28 16:43       ` Andy Shevchenko
2015-01-28 13:25 ` [PATCH 2/2] string_helpers: Change semantics of string_escape_mem Rasmus Villemoes
2015-01-28 15:05   ` Andy Shevchenko
2015-01-29 10:03 ` [PATCH v2 0/3] Two printf fixes Rasmus Villemoes
2015-01-29 10:03   ` [PATCH v2 1/3] lib/vsprintf.c: Fix potential NULL deref in hex_string Rasmus Villemoes
2015-01-29 10:43     ` Andy Shevchenko
2015-01-29 10:03   ` [PATCH v2 2/3] lib/string_helpers.c: Refactor string_escape_mem Rasmus Villemoes
2015-01-29 12:12     ` Andy Shevchenko
2015-01-29 13:10       ` Rasmus Villemoes
2015-01-29 13:37         ` Andy Shevchenko
2015-01-29 19:33           ` Jeff Epler
2015-01-30 10:14             ` Andy Shevchenko
2015-01-29 10:03   ` [PATCH v2 3/3] lib/string_helpers.c: Change semantics of string_escape_mem Rasmus Villemoes
2015-01-29 13:29     ` Andy Shevchenko
2015-01-29 14:29       ` Rasmus Villemoes
2015-01-30 10:27         ` Andy Shevchenko
2015-01-30 23:39           ` Rasmus Villemoes
2015-01-30 23:39             ` Rasmus Villemoes
2015-02-02 10:56             ` Andy Shevchenko
2015-02-09 23:44   ` [PATCH v3 0/3] Two printf fixes Rasmus Villemoes
2015-02-09 23:44     ` Rasmus Villemoes
2015-02-09 23:44     ` [PATCH v3 1/3] lib/vsprintf.c: Fix potential NULL deref in hex_string Rasmus Villemoes
2015-02-09 23:44     ` [PATCH v3 2/3] lib/string_helpers.c: Refactor string_escape_mem Rasmus Villemoes
2015-02-10 12:16       ` Andy Shevchenko
2015-02-09 23:44     ` [PATCH v3 3/3] lib/string_helpers.c: Change semantics of string_escape_mem Rasmus Villemoes
2015-02-09 23:44       ` Rasmus Villemoes
2015-02-10 12:32       ` Andy Shevchenko
2015-02-10 12:32         ` Andy Shevchenko
2015-02-10 13:02         ` Rasmus Villemoes
2015-02-10 14:22           ` Andy Shevchenko
2015-02-10 14:22             ` Andy Shevchenko
2015-02-21  1:35             ` Rasmus Villemoes [this message]
2015-02-23 12:50               ` Andy Shevchenko
2015-02-23 12:50                 ` Andy Shevchenko
2015-02-23 22:55                 ` Rasmus Villemoes
2015-02-23 22:55                   ` Rasmus Villemoes
2015-03-02 12:37                   ` Andy Shevchenko
2015-03-02 12:37                     ` Andy Shevchenko
2015-03-02 23:03                     ` Rasmus Villemoes
2015-03-03 10:26                       ` Andy Shevchenko
2015-03-03 10:26                         ` Andy Shevchenko
2015-03-03 23:20     ` [PATCH v4 0/3] Two printf fixes Rasmus Villemoes
2015-03-03 23:20       ` [PATCH v4 1/3] lib/vsprintf.c: Fix potential NULL deref in hex_string Rasmus Villemoes
2015-03-03 23:20       ` [PATCH v4 2/3] lib/string_helpers.c: Refactor string_escape_mem Rasmus Villemoes
2015-03-04 10:51         ` Andy Shevchenko
2015-03-03 23:20       ` [PATCH v4 3/3] lib/string_helpers.c: Change semantics of string_escape_mem Rasmus Villemoes
2015-03-04 11:49         ` Andy Shevchenko
2015-03-04 11:49           ` Andy Shevchenko

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