[Automated-testing] [RFC PATCH] LTP Wrapper for Syzkaller reproducers
Richard Palethorpe
rpalethorpe at suse.com
Wed Oct 9 07:24:46 PDT 2019
First attempt at wrapping the Syzkaller reproducers in the LTP library. I am
posting this in case anyone wants to experiment with it early or has a
radically different approach in mind.
This just uses exec to run the reproducer executables as per Metan's
suggestion. There is a simple script which creates a runtest file allowing it
to work with existing LTP test runners, albeit with a bit of extra work for
now.
This would benefit from the following LTP library patch:
https://patchwork.ozlabs.org/patch/935568/
Running it without KASAN and the other kernel debugging options is not a good
idea. We can easily detect when the kernel config is wrong and print a
warning or even refuse to run, but I haven't added it yet.
Having to download, compile and install the reproducers seperately is annoying
and I bet most users won't do it. We can probably automate that as part of the
install, it is just a question of how much we do as default.
---
runtest/.gitignore | 1 +
testcases/kernel/Makefile | 1 +
testcases/kernel/syzkaller-repros/.gitignore | 1 +
testcases/kernel/syzkaller-repros/Makefile | 10 +++
testcases/kernel/syzkaller-repros/README.md | 39 +++++++++
.../kernel/syzkaller-repros/gen-runtest.sh | 8 ++
testcases/kernel/syzkaller-repros/syzwrap.c | 85 +++++++++++++++++++
7 files changed, 145 insertions(+)
create mode 100644 runtest/.gitignore
create mode 100644 testcases/kernel/syzkaller-repros/.gitignore
create mode 100644 testcases/kernel/syzkaller-repros/Makefile
create mode 100644 testcases/kernel/syzkaller-repros/README.md
create mode 100755 testcases/kernel/syzkaller-repros/gen-runtest.sh
create mode 100644 testcases/kernel/syzkaller-repros/syzwrap.c
diff --git a/runtest/.gitignore b/runtest/.gitignore
new file mode 100644
index 000000000..e3725dd42
--- /dev/null
+++ b/runtest/.gitignore
@@ -0,0 +1 @@
+syzkaller-repros
diff --git a/testcases/kernel/Makefile b/testcases/kernel/Makefile
index 3319b3163..0150cfb4f 100644
--- a/testcases/kernel/Makefile
+++ b/testcases/kernel/Makefile
@@ -53,6 +53,7 @@ SUBDIRS += connectors \
sched \
security \
sound \
+ syzkaller-repros \
tracing \
uevents \
diff --git a/testcases/kernel/syzkaller-repros/.gitignore b/testcases/kernel/syzkaller-repros/.gitignore
new file mode 100644
index 000000000..dbda1c71f
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/.gitignore
@@ -0,0 +1 @@
+syzwrap
diff --git a/testcases/kernel/syzkaller-repros/Makefile b/testcases/kernel/syzkaller-repros/Makefile
new file mode 100644
index 000000000..8e74805c2
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/Makefile
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2019 Linux Test Project
+
+top_srcdir ?= ../../..
+
+include $(top_srcdir)/include/mk/testcases.mk
+
+CFLAGS += -D_GNU_SOURCE
+
+include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/syzkaller-repros/README.md b/testcases/kernel/syzkaller-repros/README.md
new file mode 100644
index 000000000..e95ae19e2
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/README.md
@@ -0,0 +1,39 @@
+LTP wrapper for Syzkaller reproducers
+=====================================
+
+This allows you to run the autogenerated bug reproducers from the Syzkaller
+fuzzer within the LTP framework. Meaning that you may use an existing test
+runner compatible with the LTP.
+
+However some extra setup is currently required.
+
+Instructions
+------------
+
+1. Download and compile the reproducers.
+2. Build the LTP as normal
+3. Use the gen-runtest.sh script to create a runtest file
+4. Install the LTP and the reproducers to the SUT
+5. Execute the tests in the syzkaller-repros runtest file
+
+For now you can download the reproducers from here:
+https://github.com/dvyukov/syzkaller-repros. Soon they will be available on
+kernel.org.
+
+The gen-runtest takes two arguments:
+
+1. The directory where the reproducer executables are currently accessible
+2. The *absolute* path to the directory where they will be on the SUT (If
+ different, can be omitted)
+
+For example:
+```
+./gen-runtest.sh ~/qa/syzkaller-repros/bin /mnt/syzkaller-repros/bin >
+~/qa/ltp-build/runtest/syzkaller-repros
+```
+
+For the LTP, just doing `make install` will copy all the relevant files
+(assuming you put the runtest file in the runtest folder). However you will
+need to copy the reproducers yourself.
+
+
diff --git a/testcases/kernel/syzkaller-repros/gen-runtest.sh b/testcases/kernel/syzkaller-repros/gen-runtest.sh
new file mode 100755
index 000000000..091818fb2
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/gen-runtest.sh
@@ -0,0 +1,8 @@
+#!/usr/bin/sh
+
+BUILD_DIR=$1
+SUT_DIR=$2
+
+for f in $(ls $BUILD_DIR); do
+ echo $f syzwrap -d ${SUT_DIR:-$BUILD_DIR} -n $f
+done
diff --git a/testcases/kernel/syzkaller-repros/syzwrap.c b/testcases/kernel/syzkaller-repros/syzwrap.c
new file mode 100644
index 000000000..7951d1819
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/syzwrap.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 Richard Palethorpe <rpalethorpe at suse.com>
+ *
+ * Run a single reproducer generated by the Syzkaller fuzzer.
+ */
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <stdio.h>
+
+#include "tst_test.h"
+#include "tst_taint.h"
+#include "tst_safe_stdio.h"
+
+static char *dir;
+static char *name;
+static char *path;
+
+static struct tst_option options[] = {
+ {"d:", &dir, "Mandatory directory containing reproducers"},
+ {"n:", &name, "Mandatory executable name of reproducer"},
+ {NULL, NULL, NULL}
+};
+
+static void setup(void)
+{
+ tst_taint_init(TST_TAINT_W | TST_TAINT_D);
+
+ if (!dir)
+ tst_brk(TBROK, "No reproducer directory specified");
+
+ if (!name)
+ tst_brk(TBROK, "No reproducer name specified");
+
+ tst_res(TINFO, "https://syzkaller.appspot.com/bug?id=%s", name);
+
+ SAFE_ASPRINTF(&path, "%s/%s", dir, name);
+ tst_res(TINFO, "%s", path);
+}
+
+static void run(void)
+{
+ unsigned int backoff = 100;
+ int rem, status, sent_kill = 0;
+ float exec_time_start = (float)tst_timeout_remaining();
+ int pid = SAFE_FORK();
+
+ if (!pid) {
+ execle(path, name, environ);
+ tst_brk(TBROK | TERRNO, "Failed to exec reproducer");
+ }
+
+ while (!waitpid(pid, &status, WNOHANG)) {
+ rem = tst_timeout_remaining();
+
+ if (!sent_kill && rem / exec_time_start < 0.98) {
+ tst_res(TINFO, "Timeout; killing reproducer");
+
+ TEST(kill(pid, SIGKILL));
+ if (TST_RET == -1)
+ tst_res(TWARN | TTERRNO, "kill() failed");
+ else
+ sent_kill = 1;
+ }
+
+ usleep(backoff);
+ backoff = MIN(2 * backoff, 1000000);
+ }
+
+ if (tst_taint_check()) {
+ tst_res(TFAIL, "Kernel is tainted");
+ } else {
+ tst_res(TPASS, "Kernel is not tainted");
+ }
+}
+
+static struct tst_test test = {
+ .setup = setup,
+ .test_all = run,
+ .options = options,
+ .needs_tmpdir = 1,
+ .forks_child = 1,
+};
--
2.23.0
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