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From: Khalid Aziz <khalid.aziz@oracle.com>
To: Michael Ellerman <mpe@ellerman.id.au>, akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, jannh@google.com, mhocko@suse.com,
	linux-mm@kvack.org, aarcange@redhat.com, fweimer@redhat.com,
	jhubbard@nvidia.com, willy@infradead.org,
	abdhalee@linux.vnet.ibm.com, joel@jms.id.au,
	keescook@chromium.org, jasone@google.com,
	davidtgoldblatt@gmail.com, trasz@freebsd.org,
	danielmicay@gmail.com
Subject: Re: [PATCH] selftests/vm: Add a test for MAP_FIXED_NOREPLACE
Date: Mon, 15 Oct 2018 01:39:22 -0600	[thread overview]
Message-ID: <eb618206-4343-6c95-4db4-91bee48dc4b2@oracle.com> (raw)
In-Reply-To: <20181013133929.28653-1-mpe@ellerman.id.au>

On 10/13/2018 07:39 AM, Michael Ellerman wrote:
> Add a test for MAP_FIXED_NOREPLACE, based on some code originally by
> Jann Horn. This would have caught the overlap bug reported by Daniel Micay.
> 
> I originally suggested to Michal that we create MAP_FIXED_NOREPLACE, but
> instead of writing a selftest I spent my time bike-shedding whether it
> should be called MAP_FIXED_SAFE/NOCLOBBER/WEAK/NEW .. mea culpa.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---

Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>

--
Khalid

>   tools/testing/selftests/vm/.gitignore         |   1 +
>   tools/testing/selftests/vm/Makefile           |   1 +
>   .../selftests/vm/map_fixed_noreplace.c        | 206 ++++++++++++++++++
>   3 files changed, 208 insertions(+)
>   create mode 100644 tools/testing/selftests/vm/map_fixed_noreplace.c
> 
> diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore
> index af5ff83f6d7f..31b3c98b6d34 100644
> --- a/tools/testing/selftests/vm/.gitignore
> +++ b/tools/testing/selftests/vm/.gitignore
> @@ -13,3 +13,4 @@ mlock-random-test
>   virtual_address_range
>   gup_benchmark
>   va_128TBswitch
> +map_fixed_noreplace
> diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
> index e94b7b14bcb2..6e67e726e5a5 100644
> --- a/tools/testing/selftests/vm/Makefile
> +++ b/tools/testing/selftests/vm/Makefile
> @@ -12,6 +12,7 @@ TEST_GEN_FILES += gup_benchmark
>   TEST_GEN_FILES += hugepage-mmap
>   TEST_GEN_FILES += hugepage-shm
>   TEST_GEN_FILES += map_hugetlb
> +TEST_GEN_FILES += map_fixed_noreplace
>   TEST_GEN_FILES += map_populate
>   TEST_GEN_FILES += mlock-random-test
>   TEST_GEN_FILES += mlock2-tests
> diff --git a/tools/testing/selftests/vm/map_fixed_noreplace.c b/tools/testing/selftests/vm/map_fixed_noreplace.c
> new file mode 100644
> index 000000000000..d91bde511268
> --- /dev/null
> +++ b/tools/testing/selftests/vm/map_fixed_noreplace.c
> @@ -0,0 +1,206 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Test that MAP_FIXED_NOREPLACE works.
> + *
> + * Copyright 2018, Jann Horn <jannh@google.com>
> + * Copyright 2018, Michael Ellerman, IBM Corporation.
> + */
> +
> +#include <sys/mman.h>
> +#include <errno.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +
> +#ifndef MAP_FIXED_NOREPLACE
> +#define MAP_FIXED_NOREPLACE 0x100000
> +#endif
> +
> +#define BASE_ADDRESS	(256ul * 1024 * 1024)
> +
> +
> +static void dump_maps(void)
> +{
> +	char cmd[32];
> +
> +	snprintf(cmd, sizeof(cmd), "cat /proc/%d/maps", getpid());
> +	system(cmd);
> +}
> +
> +int main(void)
> +{
> +	unsigned long flags, addr, size, page_size;
> +	char *p;
> +
> +	page_size = sysconf(_SC_PAGE_SIZE);
> +
> +	flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE;
> +
> +	// Check we can map all the areas we need below
> +	errno = 0;
> +	addr = BASE_ADDRESS;
> +	size = 5 * page_size;
> +	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
> +
> +	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
> +
> +	if (p == MAP_FAILED) {
> +		dump_maps();
> +		printf("Error: couldn't map the space we need for the test\n");
> +		return 1;
> +	}
> +
> +	errno = 0;
> +	if (munmap((void *)addr, 5 * page_size) != 0) {
> +		dump_maps();
> +		printf("Error: munmap failed!?\n");
> +		return 1;
> +	}
> +	printf("unmap() successful\n");
> +
> +	errno = 0;
> +	addr = BASE_ADDRESS + page_size;
> +	size = 3 * page_size;
> +	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
> +	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
> +
> +	if (p == MAP_FAILED) {
> +		dump_maps();
> +		printf("Error: first mmap() failed unexpectedly\n");
> +		return 1;
> +	}
> +
> +	/*
> +	 * Exact same mapping again:
> +	 *   base |  free  | new
> +	 *     +1 | mapped | new
> +	 *     +2 | mapped | new
> +	 *     +3 | mapped | new
> +	 *     +4 |  free  | new
> +	 */
> +	errno = 0;
> +	addr = BASE_ADDRESS;
> +	size = 5 * page_size;
> +	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
> +	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
> +
> +	if (p != MAP_FAILED) {
> +		dump_maps();
> +		printf("Error:1: mmap() succeeded when it shouldn't have\n");
> +		return 1;
> +	}
> +
> +	/*
> +	 * Second mapping contained within first:
> +	 *
> +	 *   base |  free  |
> +	 *     +1 | mapped |
> +	 *     +2 | mapped | new
> +	 *     +3 | mapped |
> +	 *     +4 |  free  |
> +	 */
> +	errno = 0;
> +	addr = BASE_ADDRESS + (2 * page_size);
> +	size = page_size;
> +	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
> +	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
> +
> +	if (p != MAP_FAILED) {
> +		dump_maps();
> +		printf("Error:2: mmap() succeeded when it shouldn't have\n");
> +		return 1;
> +	}
> +
> +	/*
> +	 * Overlap end of existing mapping:
> +	 *   base |  free  |
> +	 *     +1 | mapped |
> +	 *     +2 | mapped |
> +	 *     +3 | mapped | new
> +	 *     +4 |  free  | new
> +	 */
> +	errno = 0;
> +	addr = BASE_ADDRESS + (3 * page_size);
> +	size = 2 * page_size;
> +	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
> +	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
> +
> +	if (p != MAP_FAILED) {
> +		dump_maps();
> +		printf("Error:3: mmap() succeeded when it shouldn't have\n");
> +		return 1;
> +	}
> +
> +	/*
> +	 * Overlap start of existing mapping:
> +	 *   base |  free  | new
> +	 *     +1 | mapped | new
> +	 *     +2 | mapped |
> +	 *     +3 | mapped |
> +	 *     +4 |  free  |
> +	 */
> +	errno = 0;
> +	addr = BASE_ADDRESS;
> +	size = 2 * page_size;
> +	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
> +	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
> +
> +	if (p != MAP_FAILED) {
> +		dump_maps();
> +		printf("Error:4: mmap() succeeded when it shouldn't have\n");
> +		return 1;
> +	}
> +
> +	/*
> +	 * Adjacent to start of existing mapping:
> +	 *   base |  free  | new
> +	 *     +1 | mapped |
> +	 *     +2 | mapped |
> +	 *     +3 | mapped |
> +	 *     +4 |  free  |
> +	 */
> +	errno = 0;
> +	addr = BASE_ADDRESS;
> +	size = page_size;
> +	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
> +	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
> +
> +	if (p == MAP_FAILED) {
> +		dump_maps();
> +		printf("Error:5: mmap() failed when it shouldn't have\n");
> +		return 1;
> +	}
> +
> +	/*
> +	 * Adjacent to end of existing mapping:
> +	 *   base |  free  |
> +	 *     +1 | mapped |
> +	 *     +2 | mapped |
> +	 *     +3 | mapped |
> +	 *     +4 |  free  |  new
> +	 */
> +	errno = 0;
> +	addr = BASE_ADDRESS + (4 * page_size);
> +	size = page_size;
> +	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
> +	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
> +
> +	if (p == MAP_FAILED) {
> +		dump_maps();
> +		printf("Error:6: mmap() failed when it shouldn't have\n");
> +		return 1;
> +	}
> +
> +	addr = BASE_ADDRESS;
> +	size = 5 * page_size;
> +	if (munmap((void *)addr, size) != 0) {
> +		dump_maps();
> +		printf("Error: munmap failed!?\n");
> +		return 1;
> +	}
> +	printf("unmap() successful\n");
> +
> +	printf("OK\n");
> +	return 0;
> +}
> 


  parent reply	other threads:[~2018-10-15  7:40 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-13 13:39 [PATCH] selftests/vm: Add a test for MAP_FIXED_NOREPLACE Michael Ellerman
2018-10-14  1:16 ` Kees Cook
2018-10-15  7:39 ` Khalid Aziz [this message]
2018-10-15  8:07 ` Michal Hocko
2018-10-16  0:15   ` Michael Ellerman

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