The patch titled
Subject: tools/testing/selftests/vm/map_fixed_noreplace.c: add test for MAP_FIXED_NOREPLACE
has been added to the -mm tree. Its filename is
selftests-vm-add-a-test-for-map_fixed_noreplace.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/selftests-vm-add-a-test-for-map_fixed_noreplace.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/selftests-vm-add-a-test-for-map_fixed_noreplace.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Subject: tools/testing/selftests/vm/map_fixed_noreplace.c: add test for MAP_FIXED_NOREPLACE
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.
Link: http://lkml.kernel.org/r/20181013133929.28653-1-mpe@xxxxxxxxxxxxxx
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Khalid Aziz <khalid.aziz@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Florian Weimer <fweimer@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Abdul Haleem <abdhalee@xxxxxxxxxxxxxxxxxx>
Cc: Joel Stanley <joel@xxxxxxxxx>
Cc: Jason Evans <jasone@xxxxxxxxxx>
Cc: David Goldblatt <davidtgoldblatt@xxxxxxxxx>
Cc: Daniel Micay <danielmicay@xxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/vm/.gitignore | 1
tools/testing/selftests/vm/Makefile | 1
tools/testing/selftests/vm/map_fixed_noreplace.c | 206 +++++++++++++
3 files changed, 208 insertions(+)
--- a/tools/testing/selftests/vm/.gitignore~selftests-vm-add-a-test-for-map_fixed_noreplace
+++ a/tools/testing/selftests/vm/.gitignore
@@ -13,3 +13,4 @@ mlock-random-test
virtual_address_range
gup_benchmark
va_128TBswitch
+map_fixed_noreplace
--- a/tools/testing/selftests/vm/Makefile~selftests-vm-add-a-test-for-map_fixed_noreplace
+++ a/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
--- /dev/null
+++ a/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@xxxxxxxxxx>
+ * 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;
+}
_
Patches currently in -mm which might be from mpe@xxxxxxxxxxxxxx are
selftests-vm-add-a-test-for-map_fixed_noreplace.patch
