1 /*
2 * Copyright (C) 2012 Red Hat, Inc.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it would be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
11 *
12 * Further, this software is distributed without any warranty that it
13 * is free of the rightful claim of any third person regarding
14 * infringement or the like. Any license provided herein, whether
15 * implied or otherwise, applies only to this software file. Patent
16 * licenses, if any, provided herein do not apply to combinations of
17 * this program with other software, or any other product whatsoever.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
22 * 02110-1301, USA.
23 */
24 /*
25 * This is a reproducer for CVE-2011-2496.
26 *
27 * The normal mmap paths all avoid creating a mapping where the pgoff
28 * inside the mapping could wrap around due to overflow. However, an
29 * expanding mremap() can take such a non-wrapping mapping and make it
30 * bigger and cause a wrapping condition. There is also another case
31 * where we expand mappings hiding in plain sight: the automatic stack
32 * expansion.
33 *
34 * This program tries to remap a mapping with a new size that would
35 * wrap pgoff. Notice that it only works on 32-bit arch for now.
36 */
37
38 #define _GNU_SOURCE
39 #include "config.h"
40 #include <sys/types.h>
41 #include <sys/mman.h>
42 #include <sys/stat.h>
43 #include <sys/syscall.h>
44 #include <errno.h>
45 #include <fcntl.h>
46 #include <limits.h>
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <unistd.h>
50
51 #include "test.h"
52 #include "safe_macros.h"
53 #include "tst_kernel.h"
54
55 char *TCID = "vma03";
56 int TST_TOTAL = 1;
57
58 #ifdef __NR_mmap2
59 #define TESTFILE "testfile"
60
61 static size_t pgsz;
62 static int fd;
63
64 static void *mmap2(void *addr, size_t length, int prot,
65 int flags, int fd, off_t pgoffset);
66 static void setup(void);
67 static void cleanup(void);
68
main(int argc,char * argv[])69 int main(int argc, char *argv[])
70 {
71 int lc;
72 void *map, *remap;
73 off_t pgoff;
74
75 if (__WORDSIZE != 32 || tst_kernel_bits() != 32) {
76 tst_brkm(TCONF, NULL,
77 "test is designed for 32-bit system only.");
78 }
79
80 tst_parse_opts(argc, argv, NULL, NULL);
81
82 pgsz = sysconf(_SC_PAGE_SIZE);
83 setup();
84
85 for (lc = 0; TEST_LOOPING(lc); lc++) {
86 tst_count = 0;
87
88 fd = SAFE_OPEN(NULL, TESTFILE, O_RDWR);
89
90 /*
91 * The pgoff is counted in 4K units and must be page-aligned,
92 * hence we must align it down to page_size/4096 in a case that
93 * the system has page_size > 4K.
94 */
95 pgoff = (ULONG_MAX - 1)&(~((pgsz-1)>>12));
96 map = mmap2(NULL, pgsz, PROT_READ | PROT_WRITE, MAP_PRIVATE,
97 fd, pgoff);
98 if (map == MAP_FAILED)
99 tst_brkm(TBROK | TERRNO, cleanup, "mmap2");
100
101 remap = mremap(map, pgsz, 2 * pgsz, 0);
102 if (remap == MAP_FAILED) {
103 if (errno == EINVAL)
104 tst_resm(TPASS, "mremap failed as expected.");
105 else
106 tst_resm(TFAIL | TERRNO, "mremap");
107 munmap(map, pgsz);
108 } else {
109 tst_resm(TFAIL, "mremap succeeded unexpectedly.");
110 munmap(remap, 2 * pgsz);
111 }
112
113 close(fd);
114 }
115
116 cleanup();
117 tst_exit();
118 }
119
mmap2(void * addr,size_t length,int prot,int flags,int fd,off_t pgoffset)120 static void *mmap2(void *addr, size_t length, int prot,
121 int flags, int fd, off_t pgoffset)
122 {
123 return (void *)syscall(SYS_mmap2, addr, length, prot,
124 flags, fd, pgoffset);
125 }
126
setup(void)127 static void setup(void)
128 {
129 tst_sig(FORK, DEF_HANDLER, cleanup);
130
131 tst_tmpdir();
132
133 fd = SAFE_CREAT(NULL, TESTFILE, 0644);
134 close(fd);
135
136 TEST_PAUSE;
137 }
138
cleanup(void)139 static void cleanup(void)
140 {
141 tst_rmdir();
142 }
143 #else /* __NR_mmap2 */
main(int argc,char * argv[])144 int main(int argc, char *argv[])
145 {
146 tst_brkm(TCONF, NULL, "__NR_mmap2 is not defined on your system");
147 }
148 #endif
149