[PULL 30/31] fuzz: add virtio-scsi fuzz target

[Stefan Hajnoczi <stefanha@redhat.com>]

From: Alexander Bulekov <alxndr@bu.edu>

The virtio-scsi fuzz target sets up and fuzzes the available virtio-scsi
queues. After an element is placed on a queue, the fuzzer can select
whether to perform a kick, or continue adding elements.

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Message-id: 20200220041118.23264-22-alxndr@bu.edu
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 tests/qtest/fuzz/Makefile.include   |   1 +
 tests/qtest/fuzz/virtio_scsi_fuzz.c | 213 ++++++++++++++++++++++++++++
 2 files changed, 214 insertions(+)
 create mode 100644 tests/qtest/fuzz/virtio_scsi_fuzz.c

diff --git a/tests/qtest/fuzz/Makefile.include b/tests/qtest/fuzz/Makefile.include
index 77385777ef..cde3e9636c 100644
--- a/tests/qtest/fuzz/Makefile.include
+++ b/tests/qtest/fuzz/Makefile.include
@@ -9,6 +9,7 @@ fuzz-obj-y += tests/qtest/fuzz/qos_fuzz.o
 # Targets
 fuzz-obj-y += tests/qtest/fuzz/i440fx_fuzz.o
 fuzz-obj-y += tests/qtest/fuzz/virtio_net_fuzz.o
+fuzz-obj-y += tests/qtest/fuzz/virtio_scsi_fuzz.o
 
 FUZZ_CFLAGS += -I$(SRC_PATH)/tests -I$(SRC_PATH)/tests/qtest
 
diff --git a/tests/qtest/fuzz/virtio_scsi_fuzz.c b/tests/qtest/fuzz/virtio_scsi_fuzz.c
new file mode 100644
index 0000000000..3b95247f12
--- /dev/null
+++ b/tests/qtest/fuzz/virtio_scsi_fuzz.c
@@ -0,0 +1,213 @@
+/*
+ * virtio-serial Fuzzing Target
+ *
+ * Copyright Red Hat Inc., 2019
+ *
+ * Authors:
+ *  Alexander Bulekov   <alxndr@bu.edu>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+
+#include "tests/qtest/libqtest.h"
+#include "libqos/virtio-scsi.h"
+#include "libqos/virtio.h"
+#include "libqos/virtio-pci.h"
+#include "standard-headers/linux/virtio_ids.h"
+#include "standard-headers/linux/virtio_pci.h"
+#include "standard-headers/linux/virtio_scsi.h"
+#include "fuzz.h"
+#include "fork_fuzz.h"
+#include "qos_fuzz.h"
+
+#define PCI_SLOT                0x02
+#define PCI_FN                  0x00
+#define QVIRTIO_SCSI_TIMEOUT_US (1 * 1000 * 1000)
+
+#define MAX_NUM_QUEUES 64
+
+/* Based on tests/virtio-scsi-test.c */
+typedef struct {
+    int num_queues;
+    QVirtQueue *vq[MAX_NUM_QUEUES + 2];
+} QVirtioSCSIQueues;
+
+static QVirtioSCSIQueues *qvirtio_scsi_init(QVirtioDevice *dev, uint64_t mask)
+{
+    QVirtioSCSIQueues *vs;
+    uint64_t feat;
+    int i;
+
+    vs = g_new0(QVirtioSCSIQueues, 1);
+
+    feat = qvirtio_get_features(dev);
+    if (mask) {
+        feat &= ~QVIRTIO_F_BAD_FEATURE | mask;
+    } else {
+        feat &= ~(QVIRTIO_F_BAD_FEATURE | (1ull << VIRTIO_RING_F_EVENT_IDX));
+    }
+    qvirtio_set_features(dev, feat);
+
+    vs->num_queues = qvirtio_config_readl(dev, 0);
+
+    for (i = 0; i < vs->num_queues + 2; i++) {
+        vs->vq[i] = qvirtqueue_setup(dev, fuzz_qos_alloc, i);
+    }
+
+    qvirtio_set_driver_ok(dev);
+
+    return vs;
+}
+
+static void virtio_scsi_fuzz(QTestState *s, QVirtioSCSIQueues* queues,
+        const unsigned char *Data, size_t Size)
+{
+    /*
+     * Data is a sequence of random bytes. We split them up into "actions",
+     * followed by data:
+     * [vqa][dddddddd][vqa][dddd][vqa][dddddddddddd] ...
+     * The length of the data is specified by the preceding vqa.length
+     */
+    typedef struct vq_action {
+        uint8_t queue;
+        uint8_t length;
+        uint8_t write;
+        uint8_t next;
+        uint8_t kick;
+    } vq_action;
+
+    /* Keep track of the free head for each queue we interact with */
+    bool vq_touched[MAX_NUM_QUEUES + 2] = {0};
+    uint32_t free_head[MAX_NUM_QUEUES + 2];
+
+    QGuestAllocator *t_alloc = fuzz_qos_alloc;
+
+    QVirtioSCSI *scsi = fuzz_qos_obj;
+    QVirtioDevice *dev = scsi->vdev;
+    QVirtQueue *q;
+    vq_action vqa;
+    while (Size >= sizeof(vqa)) {
+        /* Copy the action, so we can normalize length, queue and flags */
+        memcpy(&vqa, Data, sizeof(vqa));
+
+        Data += sizeof(vqa);
+        Size -= sizeof(vqa);
+
+        vqa.queue = vqa.queue % queues->num_queues;
+        /* Cap length at the number of remaining bytes in data */
+        vqa.length = vqa.length >= Size ? Size : vqa.length;
+        vqa.write = vqa.write & 1;
+        vqa.next = vqa.next & 1;
+        vqa.kick = vqa.kick & 1;
+
+
+        q = queues->vq[vqa.queue];
+
+        /* Copy the data into ram, and place it on the virtqueue */
+        uint64_t req_addr = guest_alloc(t_alloc, vqa.length);
+        qtest_memwrite(s, req_addr, Data, vqa.length);
+        if (vq_touched[vqa.queue] == 0) {
+            vq_touched[vqa.queue] = 1;
+            free_head[vqa.queue] = qvirtqueue_add(s, q, req_addr, vqa.length,
+                    vqa.write, vqa.next);
+        } else {
+            qvirtqueue_add(s, q, req_addr, vqa.length, vqa.write , vqa.next);
+        }
+
+        if (vqa.kick) {
+            qvirtqueue_kick(s, dev, q, free_head[vqa.queue]);
+            free_head[vqa.queue] = 0;
+        }
+        Data += vqa.length;
+        Size -= vqa.length;
+    }
+    /* In the end, kick each queue we interacted with */
+    for (int i = 0; i < MAX_NUM_QUEUES + 2; i++) {
+        if (vq_touched[i]) {
+            qvirtqueue_kick(s, dev, queues->vq[i], free_head[i]);
+        }
+    }
+}
+
+static void virtio_scsi_fork_fuzz(QTestState *s,
+        const unsigned char *Data, size_t Size)
+{
+    QVirtioSCSI *scsi = fuzz_qos_obj;
+    static QVirtioSCSIQueues *queues;
+    if (!queues) {
+        queues = qvirtio_scsi_init(scsi->vdev, 0);
+    }
+    if (fork() == 0) {
+        virtio_scsi_fuzz(s, queues, Data, Size);
+        flush_events(s);
+        _Exit(0);
+    } else {
+        wait(NULL);
+    }
+}
+
+static void virtio_scsi_with_flag_fuzz(QTestState *s,
+        const unsigned char *Data, size_t Size)
+{
+    QVirtioSCSI *scsi = fuzz_qos_obj;
+    static QVirtioSCSIQueues *queues;
+
+    if (fork() == 0) {
+        if (Size >= sizeof(uint64_t)) {
+            queues = qvirtio_scsi_init(scsi->vdev, *(uint64_t *)Data);
+            virtio_scsi_fuzz(s, queues,
+                             Data + sizeof(uint64_t), Size - sizeof(uint64_t));
+            flush_events(s);
+        }
+        _Exit(0);
+    } else {
+        wait(NULL);
+    }
+}
+
+static void virtio_scsi_pre_fuzz(QTestState *s)
+{
+    qos_init_path(s);
+    counter_shm_init();
+}
+
+static void *virtio_scsi_test_setup(GString *cmd_line, void *arg)
+{
+    g_string_append(cmd_line,
+                    " -drive file=blkdebug::null-co://,"
+                    "file.image.read-zeroes=on,"
+                    "if=none,id=dr1,format=raw,file.align=4k "
+                    "-device scsi-hd,drive=dr1,lun=0,scsi-id=1");
+    return arg;
+}
+
+
+static void register_virtio_scsi_fuzz_targets(void)
+{
+    fuzz_add_qos_target(&(FuzzTarget){
+                .name = "virtio-scsi-fuzz",
+                .description = "Fuzz the virtio-scsi virtual queues, forking"
+                                "for each fuzz run",
+                .pre_vm_init = &counter_shm_init,
+                .pre_fuzz = &virtio_scsi_pre_fuzz,
+                .fuzz = virtio_scsi_fork_fuzz,},
+                "virtio-scsi",
+                &(QOSGraphTestOptions){.before = virtio_scsi_test_setup}
+                );
+
+    fuzz_add_qos_target(&(FuzzTarget){
+                .name = "virtio-scsi-flags-fuzz",
+                .description = "Fuzz the virtio-scsi virtual queues, forking"
+                "for each fuzz run (also fuzzes the virtio flags)",
+                .pre_vm_init = &counter_shm_init,
+                .pre_fuzz = &virtio_scsi_pre_fuzz,
+                .fuzz = virtio_scsi_with_flag_fuzz,},
+                "virtio-scsi",
+                &(QOSGraphTestOptions){.before = virtio_scsi_test_setup}
+                );
+}
+
+fuzz_target_init(register_virtio_scsi_fuzz_targets);
-- 
2.24.1