1 /*
2 * Copyright (C) 2012 Red Hat, Inc.
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 *
7 * This program is distributed in the hope that it would be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
10 *
11 * Further, this software is distributed without any warranty that it
12 * is free of the rightful claim of any third person regarding
13 * infringement or the like. Any license provided herein, whether
14 * implied or otherwise, applies only to this software file. Patent
15 * licenses, if any, provided herein do not apply to combinations of
16 * this program with other software, or any other product whatsoever.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 * 02110-1301, USA.
22 *
23 * thp03 - Case for spliting unaligned memory.
24 * - System will panic if failed.
25 *
26 * Modified form a reproducer for
27 * https://patchwork.kernel.org/patch/1358441/
28 * Kernel Commit id: 027ef6c87853b0a9df53175063028edb4950d476
29 * There was a bug in THP, will crash happened due to the following
30 * reason according to developers:
31 *
32 * most VM places are using pmd_none but a few are still using
33 * pmd_present. The meaning is about the same for the pmd. However
34 * pmd_present would return the wrong value on PROT_NONE ranges or in
35 * case of a non reproducible race with split_huge_page.
36 * When the code using pmd_present gets a false negative, the kernel will
37 * crash. It's just an annoying DoS with a BUG_ON triggering: no memory
38 * corruption and no data corruption (nor userland nor kernel).
39 */
40
41 #include <sys/mman.h>
42 #include <sys/types.h>
43 #include <sys/wait.h>
44 #include <fcntl.h>
45 #include <stdlib.h>
46 #include <string.h>
47 #include <errno.h>
48 #include "mem.h"
49 #include "safe_macros.h"
50 #include "test.h"
51
52 char *TCID = "thp03";
53 int TST_TOTAL = 1;
54
55 #ifdef MADV_MERGEABLE
56
57 static void thp_test(void);
58
59 static long hugepage_size;
60 static long unaligned_size;
61 static long page_size;
62
main(int argc,char ** argv)63 int main(int argc, char **argv)
64 {
65 int lc;
66
67 tst_parse_opts(argc, argv, NULL, NULL);
68
69 setup();
70
71 for (lc = 0; TEST_LOOPING(lc); lc++) {
72 tst_count = 0;
73
74 thp_test();
75 }
76 tst_resm(TPASS, "system didn't crash, pass.");
77 cleanup();
78 tst_exit();
79 }
80
thp_test(void)81 static void thp_test(void)
82 {
83 void *p;
84
85 p = mmap(NULL, unaligned_size, PROT_READ | PROT_WRITE,
86 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
87 if (p == MAP_FAILED)
88 tst_brkm(TBROK | TERRNO, cleanup, "mmap");
89
90 memset(p, 0x00, unaligned_size);
91 if (mprotect(p, unaligned_size, PROT_NONE) == -1)
92 tst_brkm(TBROK | TERRNO, cleanup, "mprotect");
93
94 if (madvise(p + hugepage_size, page_size, MADV_MERGEABLE) == -1) {
95 if (errno == EINVAL) {
96 tst_brkm(TCONF, cleanup,
97 "MADV_MERGEABLE is not enabled/supported");
98 } else {
99 tst_brkm(TBROK | TERRNO, cleanup, "madvise");
100 }
101 }
102
103 switch (fork()) {
104 case -1:
105 tst_brkm(TBROK | TERRNO, cleanup, "fork");
106 case 0:
107 exit(0);
108 default:
109 if (waitpid(-1, NULL, 0) == -1)
110 tst_brkm(TBROK | TERRNO, cleanup, "waitpid");
111 }
112 }
113
setup(void)114 void setup(void)
115 {
116 if (access(PATH_THP, F_OK) == -1)
117 tst_brkm(TCONF, NULL, "THP not enabled in kernel?");
118
119 hugepage_size = read_meminfo("Hugepagesize:") * KB;
120 unaligned_size = hugepage_size * 4 - 1;
121 page_size = SAFE_SYSCONF(NULL, _SC_PAGESIZE);
122
123 tst_sig(FORK, DEF_HANDLER, cleanup);
124 TEST_PAUSE;
125 }
126
cleanup(void)127 void cleanup(void)
128 {
129 }
130
131 #else
main(void)132 int main(void)
133 {
134 tst_brkm(TCONF, NULL, "Kernel doesn't support MADV_MERGEABLE"
135 " or you need to update your glibc-headers");
136 }
137 #endif
138