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support: Add <support/next_to_fault.h>

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Based on the implementation in resolv/tst-inet_pton.c.
This commit is contained in:
Florian Weimer 2017-11-13 17:55:12 +01:00
parent eceed67166
commit cae87e64dc
5 changed files with 120 additions and 56 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2017-11-13 Florian Weimer <fweimer@redhat.com>
* support/next_to_fault.h, support/next_to_fault.c: New files.
* support/Makefile (libsupport-routines): Add next_to_fault.
* resolv/tst-inet_pton.c (struct next_to_fault)
(next_to_fault_allocate, next_to_fault_free): Remove.
(run_one_test): Switch to <support/next_to_fault.h> interfaces.
2017-11-13 H.J. Lu <hongjiu.lu@intel.com>
* elf/dl-support.c: Include <dl-procruntime.c>.

67
resolv/tst-inet_pton.c
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@ -22,57 +22,10 @@
#include <stdio.h>
#include <string.h>
#include <support/check.h>
#include <support/next_to_fault.h>
#include <support/xunistd.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <unistd.h>
/* Memory region created by next_to_fault_allocate. */
struct next_to_fault
{
/* The user data. */
char *buffer;
size_t length;
/* The entire allocated region. */
void *region_start;
size_t region_size;
};
/* Allocate a buffer of SIZE bytes just before a page which is mapped
with PROT_NONE (so that overrunning the buffer will cause a
fault). */
static struct next_to_fault
next_to_fault_allocate (size_t size)
{
long page_size = sysconf (_SC_PAGE_SIZE);
TEST_VERIFY_EXIT (page_size > 0);
struct next_to_fault result;
result.region_size = roundup (size, page_size) + page_size;
TEST_VERIFY_EXIT (size + page_size > size);
TEST_VERIFY_EXIT (result.region_size > size);
result.region_start
= xmmap (NULL, result.region_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1);
/* Unmap the page after the allocation. */
xmprotect (result.region_start + (result.region_size - page_size),
page_size, PROT_NONE);
/* Align the allocation within the region so that it ends just
before the PROT_NONE page. */
result.buffer = result.region_start + result.region_size - page_size - size;
result.length = size;
return result;
}
/* Deallocate the memory region allocated by
next_to_fault_allocate. */
static void
next_to_fault_free (struct next_to_fault *ntf)
{
xmunmap (ntf->region_start, ntf->region_size);
*ntf = (struct next_to_fault) { NULL, };
}
struct test_case
{
/* The input data. */
@ -139,12 +92,13 @@ run_one_test (const struct test_case *t)
{
size_t test_len = strlen (t->input);
struct next_to_fault ntf_out4 = next_to_fault_allocate (4);
struct next_to_fault ntf_out6 = next_to_fault_allocate (16);
struct support_next_to_fault ntf_out4 = support_next_to_fault_allocate (4);
struct support_next_to_fault ntf_out6 = support_next_to_fault_allocate (16);
/* inet_pton requires NUL termination. */
{
struct next_to_fault ntf_in = next_to_fault_allocate (test_len + 1);
struct support_next_to_fault ntf_in
= support_next_to_fault_allocate (test_len + 1);
memcpy (ntf_in.buffer, t->input, test_len + 1);
memset (ntf_out4.buffer, 0, 4);
check_result ("inet_pton", t, AF_INET, ntf_out4.buffer,
@ -152,12 +106,13 @@ run_one_test (const struct test_case *t)
memset (ntf_out6.buffer, 0, 16);
check_result ("inet_pton", t, AF_INET6, ntf_out6.buffer,
inet_pton (AF_INET6, ntf_in.buffer, ntf_out6.buffer));
next_to_fault_free (&ntf_in);
support_next_to_fault_free (&ntf_in);
}
/* __inet_pton_length does not require NUL termination. */
{
struct next_to_fault ntf_in = next_to_fault_allocate (test_len);
struct support_next_to_fault ntf_in
= support_next_to_fault_allocate (test_len);
memcpy (ntf_in.buffer, t->input, test_len);
memset (ntf_out4.buffer, 0, 4);
check_result ("__inet_pton_length", t, AF_INET, ntf_out4.buffer,
@ -167,11 +122,11 @@ run_one_test (const struct test_case *t)
check_result ("__inet_pton_length", t, AF_INET6, ntf_out6.buffer,
__inet_pton_length (AF_INET6, ntf_in.buffer, ntf_in.length,
ntf_out6.buffer));
next_to_fault_free (&ntf_in);
support_next_to_fault_free (&ntf_in);
}
next_to_fault_free (&ntf_out4);
next_to_fault_free (&ntf_out6);
support_next_to_fault_free (&ntf_out4);
support_next_to_fault_free (&ntf_out6);
}
/* The test cases were manually crafted and the set enhanced with

1
support/Makefile
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@ -32,6 +32,7 @@ libsupport-routines = \
check_netent \
delayed_exit \
ignore_stderr \
next_to_fault \
oom_error \
resolv_test \
set_fortify_handler \

52
support/next_to_fault.c Normal file
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@ -0,0 +1,52 @@
/* Memory allocation next to an unmapped page.
Copyright (C) 2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <support/check.h>
#include <support/next_to_fault.h>
#include <support/xunistd.h>
#include <sys/mman.h>
#include <sys/param.h>
struct support_next_to_fault
support_next_to_fault_allocate (size_t size)
{
long page_size = sysconf (_SC_PAGE_SIZE);
TEST_VERIFY_EXIT (page_size > 0);
struct support_next_to_fault result;
result.region_size = roundup (size, page_size) + page_size;
if (size + page_size <= size || result.region_size <= size)
FAIL_EXIT1 ("support_next_to_fault_allocate (%zu): overflow", size);
result.region_start
= xmmap (NULL, result.region_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1);
/* Unmap the page after the allocation. */
xmprotect (result.region_start + (result.region_size - page_size),
page_size, PROT_NONE);
/* Align the allocation within the region so that it ends just
before the PROT_NONE page. */
result.buffer = result.region_start + result.region_size - page_size - size;
result.length = size;
return result;
}
void
support_next_to_fault_free (struct support_next_to_fault *ntf)
{
xmunmap (ntf->region_start, ntf->region_size);
*ntf = (struct support_next_to_fault) { NULL, };
}

48
support/next_to_fault.h Normal file
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@ -0,0 +1,48 @@
/* Memory allocation next to an unmapped page.
Copyright (C) 2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef SUPPORT_NEXT_TO_FAULT_H
#define SUPPORT_NEXT_TO_FAULT_H
#include <sys/cdefs.h>
#include <sys/types.h>
__BEGIN_DECLS
/* The memory region created by next_to_fault_allocate. */
struct support_next_to_fault
{
/* The user data. */
char *buffer;
size_t length;
/* The entire allocated region. */
void *region_start;
size_t region_size;
};
/* Allocate a buffer of SIZE bytes just before a page which is mapped
with PROT_NONE (so that overrunning the buffer will cause a
fault). */
struct support_next_to_fault support_next_to_fault_allocate (size_t size);
/* Deallocate the memory region allocated by
next_to_fault_allocate. */
void support_next_to_fault_free (struct support_next_to_fault *);
#endif /* SUPPORT_NEXT_TO_FAULT_H */