fuzz: add i440fx fuzz targets

These three targets should simply fuzz reads/writes to a couple ioports,
but they mostly serve as examples of different ways to write targets.
They demonstrate using qtest and qos for fuzzing, as well as using
rebooting and forking to reset state, or not resetting it at all.
Signed-off-by: NAlexander Bulekov <alxndr@bu.edu>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Message-id: 20200220041118.23264-20-alxndr@bu.edu
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

tests/qtest/fuzz/Makefile.include

@@ -6,6 +6,9 @@ fuzz-obj-y += tests/qtest/fuzz/fuzz.o # Fuzzer skeleton
 fuzz-obj-y += tests/qtest/fuzz/fork_fuzz.o
 fuzz-obj-y += tests/qtest/fuzz/qos_fuzz.o
 
+# Targets
+fuzz-obj-y += tests/qtest/fuzz/i440fx_fuzz.o
+
 FUZZ_CFLAGS += -I$(SRC_PATH)/tests -I$(SRC_PATH)/tests/qtest
 
 # Linker Script to force coverage-counters into known regions which we can mark

tests/qtest/fuzz/i440fx_fuzz.c

+/*
+ * I440FX 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 "qemu/main-loop.h"
+#include "tests/qtest/libqtest.h"
+#include "tests/qtest/libqos/pci.h"
+#include "tests/qtest/libqos/pci-pc.h"
+#include "fuzz.h"
+#include "fuzz/qos_fuzz.h"
+#include "fuzz/fork_fuzz.h"
+
+
+#define I440FX_PCI_HOST_BRIDGE_CFG 0xcf8
+#define I440FX_PCI_HOST_BRIDGE_DATA 0xcfc
+
+/*
+ * the input to the fuzzing functions below is a buffer of random bytes. we
+ * want to convert these bytes into a sequence of qtest or qos calls. to do
+ * this we define some opcodes:
+ */
+enum action_id {
+    WRITEB,
+    WRITEW,
+    WRITEL,
+    READB,
+    READW,
+    READL,
+    ACTION_MAX
+};
+
+static void i440fx_fuzz_qtest(QTestState *s,
+        const unsigned char *Data, size_t Size) {
+    /*
+     * loop over the Data, breaking it up into actions. each action has an
+     * opcode, address offset and value
+     */
+    typedef struct QTestFuzzAction {
+        uint8_t opcode;
+        uint8_t addr;
+        uint32_t value;
+    } QTestFuzzAction;
+    QTestFuzzAction a;
+
+    while (Size >= sizeof(a)) {
+        /* make a copy of the action so we can normalize the values in-place */
+        memcpy(&a, Data, sizeof(a));
+        /* select between two i440fx Port IO addresses */
+        uint16_t addr = a.addr % 2 ? I440FX_PCI_HOST_BRIDGE_CFG :
+                                      I440FX_PCI_HOST_BRIDGE_DATA;
+        switch (a.opcode % ACTION_MAX) {
+        case WRITEB:
+            qtest_outb(s, addr, (uint8_t)a.value);
+            break;
+        case WRITEW:
+            qtest_outw(s, addr, (uint16_t)a.value);
+            break;
+        case WRITEL:
+            qtest_outl(s, addr, (uint32_t)a.value);
+            break;
+        case READB:
+            qtest_inb(s, addr);
+            break;
+        case READW:
+            qtest_inw(s, addr);
+            break;
+        case READL:
+            qtest_inl(s, addr);
+            break;
+        }
+        /* Move to the next operation */
+        Size -= sizeof(a);
+        Data += sizeof(a);
+    }
+    flush_events(s);
+}
+
+static void i440fx_fuzz_qos(QTestState *s,
+        const unsigned char *Data, size_t Size) {
+    /*
+     * Same as i440fx_fuzz_qtest, but using QOS. devfn is incorporated into the
+     * value written over Port IO
+     */
+    typedef struct QOSFuzzAction {
+        uint8_t opcode;
+        uint8_t offset;
+        int devfn;
+        uint32_t value;
+    } QOSFuzzAction;
+
+    static QPCIBus *bus;
+    if (!bus) {
+        bus = qpci_new_pc(s, fuzz_qos_alloc);
+    }
+
+    QOSFuzzAction a;
+    while (Size >= sizeof(a)) {
+        memcpy(&a, Data, sizeof(a));
+        switch (a.opcode % ACTION_MAX) {
+        case WRITEB:
+            bus->config_writeb(bus, a.devfn, a.offset, (uint8_t)a.value);
+            break;
+        case WRITEW:
+            bus->config_writew(bus, a.devfn, a.offset, (uint16_t)a.value);
+            break;
+        case WRITEL:
+            bus->config_writel(bus, a.devfn, a.offset, (uint32_t)a.value);
+            break;
+        case READB:
+            bus->config_readb(bus, a.devfn, a.offset);
+            break;
+        case READW:
+            bus->config_readw(bus, a.devfn, a.offset);
+            break;
+        case READL:
+            bus->config_readl(bus, a.devfn, a.offset);
+            break;
+        }
+        Size -= sizeof(a);
+        Data += sizeof(a);
+    }
+    flush_events(s);
+}
+
+static void i440fx_fuzz_qos_fork(QTestState *s,
+        const unsigned char *Data, size_t Size) {
+    if (fork() == 0) {
+        i440fx_fuzz_qos(s, Data, Size);
+        _Exit(0);
+    } else {
+        wait(NULL);
+    }
+}
+
+static const char *i440fx_qtest_argv = TARGET_NAME " -machine accel=qtest"
+                                       "-m 0 -display none";
+static const char *i440fx_argv(FuzzTarget *t)
+{
+    return i440fx_qtest_argv;
+}
+
+static void fork_init(void)
+{
+    counter_shm_init();
+}
+
+static void register_pci_fuzz_targets(void)
+{
+    /* Uses simple qtest commands and reboots to reset state */
+    fuzz_add_target(&(FuzzTarget){
+                .name = "i440fx-qtest-reboot-fuzz",
+                .description = "Fuzz the i440fx using raw qtest commands and"
+                               "rebooting after each run",
+                .get_init_cmdline = i440fx_argv,
+                .fuzz = i440fx_fuzz_qtest});
+
+    /* Uses libqos and forks to prevent state leakage */
+    fuzz_add_qos_target(&(FuzzTarget){
+                .name = "i440fx-qos-fork-fuzz",
+                .description = "Fuzz the i440fx using raw qtest commands and"
+                               "rebooting after each run",
+                .pre_vm_init = &fork_init,
+                .fuzz = i440fx_fuzz_qos_fork,},
+                "i440FX-pcihost",
+                &(QOSGraphTestOptions){}
+                );
+
+    /*
+     * Uses libqos. Doesn't do anything to reset state. Note that if we were to
+     * reboot after each run, we would also have to redo the qos-related
+     * initialization (qos_init_path)
+     */
+    fuzz_add_qos_target(&(FuzzTarget){
+                .name = "i440fx-qos-noreset-fuzz",
+                .description = "Fuzz the i440fx using raw qtest commands and"
+                               "rebooting after each run",
+                .fuzz = i440fx_fuzz_qos,},
+                "i440FX-pcihost",
+                &(QOSGraphTestOptions){}
+                );
+}
+
+fuzz_target_init(register_pci_fuzz_targets);