Re: [LTP] [PATCH] syscalls/fork: add new case fork14

[Madper Xie <cxie@redhat.com>]

In-reply-to: <1927689120.7067888.1390821158238.JavaMail.root@redhat.com>

Howdy Jan,
  Thanks for your reviewing!
jstancek@redhat.com writes:

> ----- Original Message -----
>> From: "Madper Xie" <cxie@redhat.com>
>> To: ltp-list@lists.sourceforge.net
>> Sent: Monday, 27 January, 2014 8:37:01 AM
>> Subject: [LTP] [PATCH] syscalls/fork: add new case fork14
>> 
>> This testcase is a reproducer for https://lkml.org/lkml/2012/4/24/328.
>> Modified from Siddhesh Poyarekar's testcase posted on above link.
>> Since vma length in dup_mmap is calculated and stored in a unsigned
>> int, which is insufficient and hence overflows for very large maps
>> (beyond 16TB). Once overflow occurred, the fork after mmaped memory >
>> 16TB will succeed incorrectly.
>> 
>>     This case will run following loop:
>>              + mmap one (more) GB memory
>>              + fork and check return value.
>>     When mmaped more than 16 * 1024 GB, it will check if fork still fail.
>>     Expected result: Fork failed even if mmaped memory > 16 * 1024 GB
>> ---
>
> Hi,
>
> you are missing Signed-off-by line in commit message.
>
[...]
> Also it would be nice to mention upstream commit id:
>   commit 7edc8b0ac16cbaed7cb4ea4c6b95ce98d2997e84
>   Author: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
>   Date:   Tue May 29 15:06:22 2012 -0700
>     mm/fork: fix overflow in vma length when copying mmap on clone
>
Okay, I'll submit a v2 patch. :-)
> This has been fixed starting with 3.5, do we want to run this testcase
> on older kernels as well?
>
I'd say "YES". IMO, older kernels also (should) backport some patches
for bugfix.

> Regards,
> Jan
>
>>  runtest/syscalls                        |   1 +
>>  testcases/kernel/syscalls/fork/fork14.c | 118
>>  ++++++++++++++++++++++++++++++++
>>  2 files changed, 119 insertions(+)
>>  create mode 100644 testcases/kernel/syscalls/fork/fork14.c
>> 
>> diff --git a/runtest/syscalls b/runtest/syscalls
>> index afa7976..4cf90e8 100644
>> --- a/runtest/syscalls
>> +++ b/runtest/syscalls
>> @@ -277,6 +277,7 @@ fork09 fork09
>>  fork10 fork10
>>  fork11 fork11
>>  fork13 fork13 -i 1000000
>> +fork14 fork14
>>  
>>  fpathconf01 fpathconf01
>>  
>> diff --git a/testcases/kernel/syscalls/fork/fork14.c
>> b/testcases/kernel/syscalls/fork/fork14.c
>> new file mode 100644
>> index 0000000..65d124b
>> --- /dev/null
>> +++ b/testcases/kernel/syscalls/fork/fork14.c
>> @@ -0,0 +1,118 @@
>> +/*********************************************************************
>> + * Copyright (C) 2014  Red Hat, Inc.
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of version 2 of the GNU General Public
>> + * License as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it would be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>> + *
>> + * Further, this software is distributed without any warranty that it
>> + * is free of the rightful claim of any third person regarding
>> + * infringement or the like.  Any license provided herein, whether
>> + * implied or otherwise, applies only to this software file.  Patent
>> + * licenses, if any, provided herein do not apply to combinations of
>> + * this program with other software, or any other product whatsoever.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program; if not, write the Free Software
>> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
>> + * 02110-1301, USA.
>> + *
>> + * This test is a reporducer for this patch:
>> + *              https://lkml.org/lkml/2012/4/24/328
>> + * Since vma length in dup_mmap is calculated and stored in a unsigned
>> + * int, it will overflow when length of mmaped memory > 16 TB. When
>> + * overflow occur, fork will  incorrectly succeed. The patch above
>> + * fixed it.
>> + ********************************************************************/
>> +
>> +#include <sys/mman.h>
>> +#include <sys/wait.h>
>> +#include <stdio.h>
>> +#include <unistd.h>
>> +#include "test.h"
>> +#include "usctest.h"
>> +
>> +char *TCID = "fork14";
>> +int TST_TOTAL = 1;
>> +
>> +#define GB		(1024 * 1024 * 1024L)
>> +
>> +/* set mmap threshold to 16TB */
>> +#define LARGE		(16 * 1024)
>> +#define EXTENT		(16 * 1024 + 10)
>> +
>> +static void setup(void);
>> +static void cleanup(void);
>> +static int  fork_test(void);
>> +
>> +int main(int ac, char **av)
>> +{
>> +	int lc, ret;
>> +	char *msg;
>> +
>> +	msg = parse_opts(ac, av, NULL, NULL);
>> +	if (msg != NULL)
>> +		tst_brkm(TBROK, NULL, "OPTION PARSING ERROR - %s", msg);
>> +/*
>> + * Tested on ppc64/x86_64/i386/s390x. And only 64bit has this issue.
>> + * Since a 32bit program can't mmap so many memory.
>> + */
>> +#if __WORDSIZE == 32
>> +	tst_brkm(TCONF, NULL, "This test is only for 64bit.");
>> +#endif
>> +	setup();
>> +	for (lc = 0; TEST_LOOPING(lc); lc++) {
>> +		tst_count = 0;
>> +
>> +		ret = fork_test();
>> +		if (ret == 0)
>> +			tst_resm(TPASS, "fork failed as expected.");
>> +	}
>> +	cleanup();
>> +	tst_exit();
>> +}
>> +
>> +static void setup(void)
>> +{
>> +	tst_sig(FORK, DEF_HANDLER, cleanup);
>> +	TEST_PAUSE;
>> +}
>> +
>> +static void cleanup(void)
>> +{
>> +	TEST_CLEANUP;
>> +}
>> +
>> +static int fork_test(void)
>> +{
>> +	int i, ret = 0;
>> +	void *addr;
>> +
>> +	for (i = 0; i < EXTENT; i++) {
>> +		addr = mmap(NULL, (size_t) 1 * GB, PROT_READ | PROT_WRITE,
>> +			MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
>> +		if (addr == MAP_FAILED)
>> +			tst_brkm(TBROK|TERRNO, cleanup, "mmap");
>> +		switch (fork()) {
>> +		case -1:
>> +			break;
>> +		case 0:
>> +			exit(0);
>> +		default:
>> +			if (waitpid(-1, NULL, 0) == -1)
>> +				tst_brkm(TBROK|TERRNO,
>> +					cleanup, "waitpid");
>> +
>> +			if (i >= LARGE) {
>> +				tst_brkm(TFAIL, NULL,
>> +					"Fork succeeds incorrectly");
>> +				ret++;
>> +			}
>> +		}
>> +	}
>> +	return ret;
>> +}
>> --
>> 1.8.5.3
>> 
>> 
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-- 
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