| /* |
| * Generic Virtual-Device Fuzzing Target |
| * |
| * Copyright Red Hat Inc., 2020 |
| * |
| * 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 <wordexp.h> |
| |
| #include "hw/core/cpu.h" |
| #include "tests/qtest/libqos/libqtest.h" |
| #include "tests/qtest/libqos/pci-pc.h" |
| #include "fuzz.h" |
| #include "fork_fuzz.h" |
| #include "exec/address-spaces.h" |
| #include "string.h" |
| #include "exec/memory.h" |
| #include "exec/ramblock.h" |
| #include "exec/address-spaces.h" |
| #include "hw/qdev-core.h" |
| #include "hw/pci/pci.h" |
| #include "hw/boards.h" |
| #include "generic_fuzz_configs.h" |
| #include "hw/mem/sparse-mem.h" |
| |
| /* |
| * SEPARATOR is used to separate "operations" in the fuzz input |
| */ |
| #define SEPARATOR "FUZZ" |
| |
| enum cmds { |
| OP_IN, |
| OP_OUT, |
| OP_READ, |
| OP_WRITE, |
| OP_PCI_READ, |
| OP_PCI_WRITE, |
| OP_DISABLE_PCI, |
| OP_ADD_DMA_PATTERN, |
| OP_CLEAR_DMA_PATTERNS, |
| OP_CLOCK_STEP, |
| }; |
| |
| #define DEFAULT_TIMEOUT_US 100000 |
| #define USEC_IN_SEC 1000000000 |
| |
| #define MAX_DMA_FILL_SIZE 0x10000 |
| |
| #define PCI_HOST_BRIDGE_CFG 0xcf8 |
| #define PCI_HOST_BRIDGE_DATA 0xcfc |
| |
| typedef struct { |
| ram_addr_t addr; |
| ram_addr_t size; /* The number of bytes until the end of the I/O region */ |
| } address_range; |
| |
| static useconds_t timeout = DEFAULT_TIMEOUT_US; |
| |
| static bool qtest_log_enabled; |
| |
| MemoryRegion *sparse_mem_mr; |
| |
| /* |
| * A pattern used to populate a DMA region or perform a memwrite. This is |
| * useful for e.g. populating tables of unique addresses. |
| * Example {.index = 1; .stride = 2; .len = 3; .data = "\x00\x01\x02"} |
| * Renders as: 00 01 02 00 03 02 00 05 02 00 07 02 ... |
| */ |
| typedef struct { |
| uint8_t index; /* Index of a byte to increment by stride */ |
| uint8_t stride; /* Increment each index'th byte by this amount */ |
| size_t len; |
| const uint8_t *data; |
| } pattern; |
| |
| /* Avoid filling the same DMA region between MMIO/PIO commands ? */ |
| static bool avoid_double_fetches; |
| |
| static QTestState *qts_global; /* Need a global for the DMA callback */ |
| |
| /* |
| * List of memory regions that are children of QOM objects specified by the |
| * user for fuzzing. |
| */ |
| static GHashTable *fuzzable_memoryregions; |
| static GPtrArray *fuzzable_pci_devices; |
| |
| struct get_io_cb_info { |
| int index; |
| int found; |
| address_range result; |
| }; |
| |
| static bool get_io_address_cb(Int128 start, Int128 size, |
| const MemoryRegion *mr, |
| hwaddr offset_in_region, |
| void *opaque) |
| { |
| struct get_io_cb_info *info = opaque; |
| if (g_hash_table_lookup(fuzzable_memoryregions, mr)) { |
| if (info->index == 0) { |
| info->result.addr = (ram_addr_t)start; |
| info->result.size = (ram_addr_t)size; |
| info->found = 1; |
| return true; |
| } |
| info->index--; |
| } |
| return false; |
| } |
| |
| /* |
| * List of dma regions populated since the last fuzzing command. Used to ensure |
| * that we only write to each DMA address once, to avoid race conditions when |
| * building reproducers. |
| */ |
| static GArray *dma_regions; |
| |
| static GArray *dma_patterns; |
| static int dma_pattern_index; |
| static bool pci_disabled; |
| |
| /* |
| * Allocate a block of memory and populate it with a pattern. |
| */ |
| static void *pattern_alloc(pattern p, size_t len) |
| { |
| int i; |
| uint8_t *buf = g_malloc(len); |
| uint8_t sum = 0; |
| |
| for (i = 0; i < len; ++i) { |
| buf[i] = p.data[i % p.len]; |
| if ((i % p.len) == p.index) { |
| buf[i] += sum; |
| sum += p.stride; |
| } |
| } |
| return buf; |
| } |
| |
| static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr) |
| { |
| unsigned access_size_max = mr->ops->valid.max_access_size; |
| |
| /* |
| * Regions are assumed to support 1-4 byte accesses unless |
| * otherwise specified. |
| */ |
| if (access_size_max == 0) { |
| access_size_max = 4; |
| } |
| |
| /* Bound the maximum access by the alignment of the address. */ |
| if (!mr->ops->impl.unaligned) { |
| unsigned align_size_max = addr & -addr; |
| if (align_size_max != 0 && align_size_max < access_size_max) { |
| access_size_max = align_size_max; |
| } |
| } |
| |
| /* Don't attempt accesses larger than the maximum. */ |
| if (l > access_size_max) { |
| l = access_size_max; |
| } |
| l = pow2floor(l); |
| |
| return l; |
| } |
| |
| /* |
| * Call-back for functions that perform DMA reads from guest memory. Confirm |
| * that the region has not already been populated since the last loop in |
| * generic_fuzz(), avoiding potential race-conditions, which we don't have |
| * a good way for reproducing right now. |
| */ |
| void fuzz_dma_read_cb(size_t addr, size_t len, MemoryRegion *mr) |
| { |
| /* Are we in the generic-fuzzer or are we using another fuzz-target? */ |
| if (!qts_global) { |
| return; |
| } |
| |
| /* |
| * Return immediately if: |
| * - We have no DMA patterns defined |
| * - The length of the DMA read request is zero |
| * - The DMA read is hitting an MR other than the machine's main RAM |
| * - The DMA request hits past the bounds of our RAM |
| */ |
| if (dma_patterns->len == 0 |
| || len == 0 |
| || (mr != current_machine->ram && mr != sparse_mem_mr)) { |
| return; |
| } |
| |
| /* |
| * If we overlap with any existing dma_regions, split the range and only |
| * populate the non-overlapping parts. |
| */ |
| address_range region; |
| bool double_fetch = false; |
| for (int i = 0; |
| i < dma_regions->len && (avoid_double_fetches || qtest_log_enabled); |
| ++i) { |
| region = g_array_index(dma_regions, address_range, i); |
| if (addr < region.addr + region.size && addr + len > region.addr) { |
| double_fetch = true; |
| if (addr < region.addr |
| && avoid_double_fetches) { |
| fuzz_dma_read_cb(addr, region.addr - addr, mr); |
| } |
| if (addr + len > region.addr + region.size |
| && avoid_double_fetches) { |
| fuzz_dma_read_cb(region.addr + region.size, |
| addr + len - (region.addr + region.size), mr); |
| } |
| return; |
| } |
| } |
| |
| /* Cap the length of the DMA access to something reasonable */ |
| len = MIN(len, MAX_DMA_FILL_SIZE); |
| |
| address_range ar = {addr, len}; |
| g_array_append_val(dma_regions, ar); |
| pattern p = g_array_index(dma_patterns, pattern, dma_pattern_index); |
| void *buf_base = pattern_alloc(p, ar.size); |
| void *buf = buf_base; |
| hwaddr l, addr1; |
| MemoryRegion *mr1; |
| while (len > 0) { |
| l = len; |
| mr1 = address_space_translate(first_cpu->as, |
| addr, &addr1, &l, true, |
| MEMTXATTRS_UNSPECIFIED); |
| |
| if (!(memory_region_is_ram(mr1) || |
| memory_region_is_romd(mr1)) && mr1 != sparse_mem_mr) { |
| l = memory_access_size(mr1, l, addr1); |
| } else { |
| /* ROM/RAM case */ |
| if (qtest_log_enabled) { |
| /* |
| * With QTEST_LOG, use a normal, slow QTest memwrite. Prefix the log |
| * that will be written by qtest.c with a DMA tag, so we can reorder |
| * the resulting QTest trace so the DMA fills precede the last PIO/MMIO |
| * command. |
| */ |
| fprintf(stderr, "[DMA] "); |
| if (double_fetch) { |
| fprintf(stderr, "[DOUBLE-FETCH] "); |
| } |
| fflush(stderr); |
| } |
| qtest_memwrite(qts_global, addr, buf, l); |
| } |
| len -= l; |
| buf += l; |
| addr += l; |
| |
| } |
| g_free(buf_base); |
| |
| /* Increment the index of the pattern for the next DMA access */ |
| dma_pattern_index = (dma_pattern_index + 1) % dma_patterns->len; |
| } |
| |
| /* |
| * Here we want to convert a fuzzer-provided [io-region-index, offset] to |
| * a physical address. To do this, we iterate over all of the matched |
| * MemoryRegions. Check whether each region exists within the particular io |
| * space. Return the absolute address of the offset within the index'th region |
| * that is a subregion of the io_space and the distance until the end of the |
| * memory region. |
| */ |
| static bool get_io_address(address_range *result, AddressSpace *as, |
| uint8_t index, |
| uint32_t offset) { |
| FlatView *view; |
| view = as->current_map; |
| g_assert(view); |
| struct get_io_cb_info cb_info = {}; |
| |
| cb_info.index = index; |
| |
| /* |
| * Loop around the FlatView until we match "index" number of |
| * fuzzable_memoryregions, or until we know that there are no matching |
| * memory_regions. |
| */ |
| do { |
| flatview_for_each_range(view, get_io_address_cb , &cb_info); |
| } while (cb_info.index != index && !cb_info.found); |
| |
| *result = cb_info.result; |
| if (result->size) { |
| offset = offset % result->size; |
| result->addr += offset; |
| result->size -= offset; |
| } |
| return cb_info.found; |
| } |
| |
| static bool get_pio_address(address_range *result, |
| uint8_t index, uint16_t offset) |
| { |
| /* |
| * PIO BARs can be set past the maximum port address (0xFFFF). Thus, result |
| * can contain an addr that extends past the PIO space. When we pass this |
| * address to qtest_in/qtest_out, it is cast to a uint16_t, so we might end |
| * up fuzzing a completely different MemoryRegion/Device. Therefore, check |
| * that the address here is within the PIO space limits. |
| */ |
| bool found = get_io_address(result, &address_space_io, index, offset); |
| return result->addr <= 0xFFFF ? found : false; |
| } |
| |
| static bool get_mmio_address(address_range *result, |
| uint8_t index, uint32_t offset) |
| { |
| return get_io_address(result, &address_space_memory, index, offset); |
| } |
| |
| static void op_in(QTestState *s, const unsigned char * data, size_t len) |
| { |
| enum Sizes {Byte, Word, Long, end_sizes}; |
| struct { |
| uint8_t size; |
| uint8_t base; |
| uint16_t offset; |
| } a; |
| address_range abs; |
| |
| if (len < sizeof(a)) { |
| return; |
| } |
| memcpy(&a, data, sizeof(a)); |
| if (get_pio_address(&abs, a.base, a.offset) == 0) { |
| return; |
| } |
| |
| switch (a.size %= end_sizes) { |
| case Byte: |
| qtest_inb(s, abs.addr); |
| break; |
| case Word: |
| if (abs.size >= 2) { |
| qtest_inw(s, abs.addr); |
| } |
| break; |
| case Long: |
| if (abs.size >= 4) { |
| qtest_inl(s, abs.addr); |
| } |
| break; |
| } |
| } |
| |
| static void op_out(QTestState *s, const unsigned char * data, size_t len) |
| { |
| enum Sizes {Byte, Word, Long, end_sizes}; |
| struct { |
| uint8_t size; |
| uint8_t base; |
| uint16_t offset; |
| uint32_t value; |
| } a; |
| address_range abs; |
| |
| if (len < sizeof(a)) { |
| return; |
| } |
| memcpy(&a, data, sizeof(a)); |
| |
| if (get_pio_address(&abs, a.base, a.offset) == 0) { |
| return; |
| } |
| |
| switch (a.size %= end_sizes) { |
| case Byte: |
| qtest_outb(s, abs.addr, a.value & 0xFF); |
| break; |
| case Word: |
| if (abs.size >= 2) { |
| qtest_outw(s, abs.addr, a.value & 0xFFFF); |
| } |
| break; |
| case Long: |
| if (abs.size >= 4) { |
| qtest_outl(s, abs.addr, a.value); |
| } |
| break; |
| } |
| } |
| |
| static void op_read(QTestState *s, const unsigned char * data, size_t len) |
| { |
| enum Sizes {Byte, Word, Long, Quad, end_sizes}; |
| struct { |
| uint8_t size; |
| uint8_t base; |
| uint32_t offset; |
| } a; |
| address_range abs; |
| |
| if (len < sizeof(a)) { |
| return; |
| } |
| memcpy(&a, data, sizeof(a)); |
| |
| if (get_mmio_address(&abs, a.base, a.offset) == 0) { |
| return; |
| } |
| |
| switch (a.size %= end_sizes) { |
| case Byte: |
| qtest_readb(s, abs.addr); |
| break; |
| case Word: |
| if (abs.size >= 2) { |
| qtest_readw(s, abs.addr); |
| } |
| break; |
| case Long: |
| if (abs.size >= 4) { |
| qtest_readl(s, abs.addr); |
| } |
| break; |
| case Quad: |
| if (abs.size >= 8) { |
| qtest_readq(s, abs.addr); |
| } |
| break; |
| } |
| } |
| |
| static void op_write(QTestState *s, const unsigned char * data, size_t len) |
| { |
| enum Sizes {Byte, Word, Long, Quad, end_sizes}; |
| struct { |
| uint8_t size; |
| uint8_t base; |
| uint32_t offset; |
| uint64_t value; |
| } a; |
| address_range abs; |
| |
| if (len < sizeof(a)) { |
| return; |
| } |
| memcpy(&a, data, sizeof(a)); |
| |
| if (get_mmio_address(&abs, a.base, a.offset) == 0) { |
| return; |
| } |
| |
| switch (a.size %= end_sizes) { |
| case Byte: |
| qtest_writeb(s, abs.addr, a.value & 0xFF); |
| break; |
| case Word: |
| if (abs.size >= 2) { |
| qtest_writew(s, abs.addr, a.value & 0xFFFF); |
| } |
| break; |
| case Long: |
| if (abs.size >= 4) { |
| qtest_writel(s, abs.addr, a.value & 0xFFFFFFFF); |
| } |
| break; |
| case Quad: |
| if (abs.size >= 8) { |
| qtest_writeq(s, abs.addr, a.value); |
| } |
| break; |
| } |
| } |
| |
| static void op_pci_read(QTestState *s, const unsigned char * data, size_t len) |
| { |
| enum Sizes {Byte, Word, Long, end_sizes}; |
| struct { |
| uint8_t size; |
| uint8_t base; |
| uint8_t offset; |
| } a; |
| if (len < sizeof(a) || fuzzable_pci_devices->len == 0 || pci_disabled) { |
| return; |
| } |
| memcpy(&a, data, sizeof(a)); |
| PCIDevice *dev = g_ptr_array_index(fuzzable_pci_devices, |
| a.base % fuzzable_pci_devices->len); |
| int devfn = dev->devfn; |
| qtest_outl(s, PCI_HOST_BRIDGE_CFG, (1U << 31) | (devfn << 8) | a.offset); |
| switch (a.size %= end_sizes) { |
| case Byte: |
| qtest_inb(s, PCI_HOST_BRIDGE_DATA); |
| break; |
| case Word: |
| qtest_inw(s, PCI_HOST_BRIDGE_DATA); |
| break; |
| case Long: |
| qtest_inl(s, PCI_HOST_BRIDGE_DATA); |
| break; |
| } |
| } |
| |
| static void op_pci_write(QTestState *s, const unsigned char * data, size_t len) |
| { |
| enum Sizes {Byte, Word, Long, end_sizes}; |
| struct { |
| uint8_t size; |
| uint8_t base; |
| uint8_t offset; |
| uint32_t value; |
| } a; |
| if (len < sizeof(a) || fuzzable_pci_devices->len == 0 || pci_disabled) { |
| return; |
| } |
| memcpy(&a, data, sizeof(a)); |
| PCIDevice *dev = g_ptr_array_index(fuzzable_pci_devices, |
| a.base % fuzzable_pci_devices->len); |
| int devfn = dev->devfn; |
| qtest_outl(s, PCI_HOST_BRIDGE_CFG, (1U << 31) | (devfn << 8) | a.offset); |
| switch (a.size %= end_sizes) { |
| case Byte: |
| qtest_outb(s, PCI_HOST_BRIDGE_DATA, a.value & 0xFF); |
| break; |
| case Word: |
| qtest_outw(s, PCI_HOST_BRIDGE_DATA, a.value & 0xFFFF); |
| break; |
| case Long: |
| qtest_outl(s, PCI_HOST_BRIDGE_DATA, a.value & 0xFFFFFFFF); |
| break; |
| } |
| } |
| |
| static void op_add_dma_pattern(QTestState *s, |
| const unsigned char *data, size_t len) |
| { |
| struct { |
| /* |
| * index and stride can be used to increment the index-th byte of the |
| * pattern by the value stride, for each loop of the pattern. |
| */ |
| uint8_t index; |
| uint8_t stride; |
| } a; |
| |
| if (len < sizeof(a) + 1) { |
| return; |
| } |
| memcpy(&a, data, sizeof(a)); |
| pattern p = {a.index, a.stride, len - sizeof(a), data + sizeof(a)}; |
| p.index = a.index % p.len; |
| g_array_append_val(dma_patterns, p); |
| return; |
| } |
| |
| static void op_clear_dma_patterns(QTestState *s, |
| const unsigned char *data, size_t len) |
| { |
| g_array_set_size(dma_patterns, 0); |
| dma_pattern_index = 0; |
| } |
| |
| static void op_clock_step(QTestState *s, const unsigned char *data, size_t len) |
| { |
| qtest_clock_step_next(s); |
| } |
| |
| static void op_disable_pci(QTestState *s, const unsigned char *data, size_t len) |
| { |
| pci_disabled = true; |
| } |
| |
| static void handle_timeout(int sig) |
| { |
| if (qtest_log_enabled) { |
| fprintf(stderr, "[Timeout]\n"); |
| fflush(stderr); |
| } |
| |
| /* |
| * If there is a crash, libfuzzer/ASAN forks a child to run an |
| * "llvm-symbolizer" process for printing out a pretty stacktrace. It |
| * communicates with this child using a pipe. If we timeout+Exit, while |
| * libfuzzer is still communicating with the llvm-symbolizer child, we will |
| * be left with an orphan llvm-symbolizer process. Sometimes, this appears |
| * to lead to a deadlock in the forkserver. Use waitpid to check if there |
| * are any waitable children. If so, exit out of the signal-handler, and |
| * let libfuzzer finish communicating with the child, and exit, on its own. |
| */ |
| if (waitpid(-1, NULL, WNOHANG) == 0) { |
| return; |
| } |
| |
| _Exit(0); |
| } |
| |
| /* |
| * Here, we interpret random bytes from the fuzzer, as a sequence of commands. |
| * Some commands can be variable-width, so we use a separator, SEPARATOR, to |
| * specify the boundaries between commands. SEPARATOR is used to separate |
| * "operations" in the fuzz input. Why use a separator, instead of just using |
| * the operations' length to identify operation boundaries? |
| * 1. This is a simple way to support variable-length operations |
| * 2. This adds "stability" to the input. |
| * For example take the input "AbBcgDefg", where there is no separator and |
| * Opcodes are capitalized. |
| * Simply, by removing the first byte, we end up with a very different |
| * sequence: |
| * BbcGdefg... |
| * By adding a separator, we avoid this problem: |
| * Ab SEP Bcg SEP Defg -> B SEP Bcg SEP Defg |
| * Since B uses two additional bytes as operands, the first "B" will be |
| * ignored. The fuzzer actively tries to reduce inputs, so such unused |
| * bytes are likely to be pruned, eventually. |
| * |
| * SEPARATOR is trivial for the fuzzer to discover when using ASan. Optionally, |
| * SEPARATOR can be manually specified as a dictionary value (see libfuzzer's |
| * -dict), though this should not be necessary. |
| * |
| * As a result, the stream of bytes is converted into a sequence of commands. |
| * In a simplified example where SEPARATOR is 0xFF: |
| * 00 01 02 FF 03 04 05 06 FF 01 FF ... |
| * becomes this sequence of commands: |
| * 00 01 02 -> op00 (0102) -> in (0102, 2) |
| * 03 04 05 06 -> op03 (040506) -> write (040506, 3) |
| * 01 -> op01 (-,0) -> out (-,0) |
| * ... |
| * |
| * Note here that it is the job of the individual opcode functions to check |
| * that enough data was provided. I.e. in the last command out (,0), out needs |
| * to check that there is not enough data provided to select an address/value |
| * for the operation. |
| */ |
| static void generic_fuzz(QTestState *s, const unsigned char *Data, size_t Size) |
| { |
| void (*ops[]) (QTestState *s, const unsigned char* , size_t) = { |
| [OP_IN] = op_in, |
| [OP_OUT] = op_out, |
| [OP_READ] = op_read, |
| [OP_WRITE] = op_write, |
| [OP_PCI_READ] = op_pci_read, |
| [OP_PCI_WRITE] = op_pci_write, |
| [OP_DISABLE_PCI] = op_disable_pci, |
| [OP_ADD_DMA_PATTERN] = op_add_dma_pattern, |
| [OP_CLEAR_DMA_PATTERNS] = op_clear_dma_patterns, |
| [OP_CLOCK_STEP] = op_clock_step, |
| }; |
| const unsigned char *cmd = Data; |
| const unsigned char *nextcmd; |
| size_t cmd_len; |
| uint8_t op; |
| |
| if (fork() == 0) { |
| /* |
| * Sometimes the fuzzer will find inputs that take quite a long time to |
| * process. Often times, these inputs do not result in new coverage. |
| * Even if these inputs might be interesting, they can slow down the |
| * fuzzer, overall. Set a timeout to avoid hurting performance, too much |
| */ |
| if (timeout) { |
| struct sigaction sact; |
| struct itimerval timer; |
| |
| sigemptyset(&sact.sa_mask); |
| sact.sa_flags = SA_NODEFER; |
| sact.sa_handler = handle_timeout; |
| sigaction(SIGALRM, &sact, NULL); |
| |
| memset(&timer, 0, sizeof(timer)); |
| timer.it_value.tv_sec = timeout / USEC_IN_SEC; |
| timer.it_value.tv_usec = timeout % USEC_IN_SEC; |
| setitimer(ITIMER_VIRTUAL, &timer, NULL); |
| } |
| |
| op_clear_dma_patterns(s, NULL, 0); |
| pci_disabled = false; |
| |
| while (cmd && Size) { |
| /* Get the length until the next command or end of input */ |
| nextcmd = memmem(cmd, Size, SEPARATOR, strlen(SEPARATOR)); |
| cmd_len = nextcmd ? nextcmd - cmd : Size; |
| |
| if (cmd_len > 0) { |
| /* Interpret the first byte of the command as an opcode */ |
| op = *cmd % (sizeof(ops) / sizeof((ops)[0])); |
| ops[op](s, cmd + 1, cmd_len - 1); |
| |
| /* Run the main loop */ |
| flush_events(s); |
| } |
| /* Advance to the next command */ |
| cmd = nextcmd ? nextcmd + sizeof(SEPARATOR) - 1 : nextcmd; |
| Size = Size - (cmd_len + sizeof(SEPARATOR) - 1); |
| g_array_set_size(dma_regions, 0); |
| } |
| _Exit(0); |
| } else { |
| flush_events(s); |
| wait(0); |
| } |
| } |
| |
| static void usage(void) |
| { |
| printf("Please specify the following environment variables:\n"); |
| printf("QEMU_FUZZ_ARGS= the command line arguments passed to qemu\n"); |
| printf("QEMU_FUZZ_OBJECTS= " |
| "a space separated list of QOM type names for objects to fuzz\n"); |
| printf("Optionally: QEMU_AVOID_DOUBLE_FETCH= " |
| "Try to avoid racy DMA double fetch bugs? %d by default\n", |
| avoid_double_fetches); |
| printf("Optionally: QEMU_FUZZ_TIMEOUT= Specify a custom timeout (us). " |
| "0 to disable. %d by default\n", timeout); |
| exit(0); |
| } |
| |
| static int locate_fuzz_memory_regions(Object *child, void *opaque) |
| { |
| const char *name; |
| MemoryRegion *mr; |
| if (object_dynamic_cast(child, TYPE_MEMORY_REGION)) { |
| mr = MEMORY_REGION(child); |
| if ((memory_region_is_ram(mr) || |
| memory_region_is_ram_device(mr) || |
| memory_region_is_rom(mr)) == false) { |
| name = object_get_canonical_path_component(child); |
| /* |
| * We don't want duplicate pointers to the same MemoryRegion, so |
| * try to remove copies of the pointer, before adding it. |
| */ |
| g_hash_table_insert(fuzzable_memoryregions, mr, (gpointer)true); |
| } |
| } |
| return 0; |
| } |
| |
| static int locate_fuzz_objects(Object *child, void *opaque) |
| { |
| char *pattern = opaque; |
| if (g_pattern_match_simple(pattern, object_get_typename(child))) { |
| /* Find and save ptrs to any child MemoryRegions */ |
| object_child_foreach_recursive(child, locate_fuzz_memory_regions, NULL); |
| |
| /* |
| * We matched an object. If its a PCI device, store a pointer to it so |
| * we can map BARs and fuzz its config space. |
| */ |
| if (object_dynamic_cast(OBJECT(child), TYPE_PCI_DEVICE)) { |
| /* |
| * Don't want duplicate pointers to the same PCIDevice, so remove |
| * copies of the pointer, before adding it. |
| */ |
| g_ptr_array_remove_fast(fuzzable_pci_devices, PCI_DEVICE(child)); |
| g_ptr_array_add(fuzzable_pci_devices, PCI_DEVICE(child)); |
| } |
| } else if (object_dynamic_cast(OBJECT(child), TYPE_MEMORY_REGION)) { |
| if (g_pattern_match_simple(pattern, |
| object_get_canonical_path_component(child))) { |
| MemoryRegion *mr; |
| mr = MEMORY_REGION(child); |
| if ((memory_region_is_ram(mr) || |
| memory_region_is_ram_device(mr) || |
| memory_region_is_rom(mr)) == false) { |
| g_hash_table_insert(fuzzable_memoryregions, mr, (gpointer)true); |
| } |
| } |
| } |
| return 0; |
| } |
| |
| |
| static void pci_enum(gpointer pcidev, gpointer bus) |
| { |
| PCIDevice *dev = pcidev; |
| QPCIDevice *qdev; |
| int i; |
| |
| qdev = qpci_device_find(bus, dev->devfn); |
| g_assert(qdev != NULL); |
| for (i = 0; i < 6; i++) { |
| if (dev->io_regions[i].size) { |
| qpci_iomap(qdev, i, NULL); |
| } |
| } |
| qpci_device_enable(qdev); |
| g_free(qdev); |
| } |
| |
| static void generic_pre_fuzz(QTestState *s) |
| { |
| GHashTableIter iter; |
| MemoryRegion *mr; |
| QPCIBus *pcibus; |
| char **result; |
| |
| if (!getenv("QEMU_FUZZ_OBJECTS")) { |
| usage(); |
| } |
| if (getenv("QTEST_LOG")) { |
| qtest_log_enabled = 1; |
| } |
| if (getenv("QEMU_AVOID_DOUBLE_FETCH")) { |
| avoid_double_fetches = 1; |
| } |
| if (getenv("QEMU_FUZZ_TIMEOUT")) { |
| timeout = g_ascii_strtoll(getenv("QEMU_FUZZ_TIMEOUT"), NULL, 0); |
| } |
| qts_global = s; |
| |
| /* |
| * Create a special device that we can use to back DMA buffers at very |
| * high memory addresses |
| */ |
| sparse_mem_mr = sparse_mem_init(0, UINT64_MAX); |
| |
| dma_regions = g_array_new(false, false, sizeof(address_range)); |
| dma_patterns = g_array_new(false, false, sizeof(pattern)); |
| |
| fuzzable_memoryregions = g_hash_table_new(NULL, NULL); |
| fuzzable_pci_devices = g_ptr_array_new(); |
| |
| result = g_strsplit(getenv("QEMU_FUZZ_OBJECTS"), " ", -1); |
| for (int i = 0; result[i] != NULL; i++) { |
| printf("Matching objects by name %s\n", result[i]); |
| object_child_foreach_recursive(qdev_get_machine(), |
| locate_fuzz_objects, |
| result[i]); |
| } |
| g_strfreev(result); |
| printf("This process will try to fuzz the following MemoryRegions:\n"); |
| |
| g_hash_table_iter_init(&iter, fuzzable_memoryregions); |
| while (g_hash_table_iter_next(&iter, (gpointer)&mr, NULL)) { |
| printf(" * %s (size %lx)\n", |
| object_get_canonical_path_component(&(mr->parent_obj)), |
| (uint64_t)mr->size); |
| } |
| |
| if (!g_hash_table_size(fuzzable_memoryregions)) { |
| printf("No fuzzable memory regions found...\n"); |
| exit(1); |
| } |
| |
| pcibus = qpci_new_pc(s, NULL); |
| g_ptr_array_foreach(fuzzable_pci_devices, pci_enum, pcibus); |
| qpci_free_pc(pcibus); |
| |
| counter_shm_init(); |
| } |
| |
| /* |
| * When libfuzzer gives us two inputs to combine, return a new input with the |
| * following structure: |
| * |
| * Input 1 (data1) |
| * SEPARATOR |
| * Clear out the DMA Patterns |
| * SEPARATOR |
| * Disable the pci_read/write instructions |
| * SEPARATOR |
| * Input 2 (data2) |
| * |
| * The idea is to collate the core behaviors of the two inputs. |
| * For example: |
| * Input 1: maps a device's BARs, sets up three DMA patterns, and triggers |
| * device functionality A |
| * Input 2: maps a device's BARs, sets up one DMA pattern, and triggers device |
| * functionality B |
| * |
| * This function attempts to produce an input that: |
| * Ouptut: maps a device's BARs, set up three DMA patterns, triggers |
| * functionality A device, replaces the DMA patterns with a single |
| * patten, and triggers device functionality B. |
| */ |
| static size_t generic_fuzz_crossover(const uint8_t *data1, size_t size1, const |
| uint8_t *data2, size_t size2, uint8_t *out, |
| size_t max_out_size, unsigned int seed) |
| { |
| size_t copy_len = 0, size = 0; |
| |
| /* Check that we have enough space for data1 and at least part of data2 */ |
| if (max_out_size <= size1 + strlen(SEPARATOR) * 3 + 2) { |
| return 0; |
| } |
| |
| /* Copy_Len in the first input */ |
| copy_len = size1; |
| memcpy(out + size, data1, copy_len); |
| size += copy_len; |
| max_out_size -= copy_len; |
| |
| /* Append a separator */ |
| copy_len = strlen(SEPARATOR); |
| memcpy(out + size, SEPARATOR, copy_len); |
| size += copy_len; |
| max_out_size -= copy_len; |
| |
| /* Clear out the DMA Patterns */ |
| copy_len = 1; |
| if (copy_len) { |
| out[size] = OP_CLEAR_DMA_PATTERNS; |
| } |
| size += copy_len; |
| max_out_size -= copy_len; |
| |
| /* Append a separator */ |
| copy_len = strlen(SEPARATOR); |
| memcpy(out + size, SEPARATOR, copy_len); |
| size += copy_len; |
| max_out_size -= copy_len; |
| |
| /* Disable PCI ops. Assume data1 took care of setting up PCI */ |
| copy_len = 1; |
| if (copy_len) { |
| out[size] = OP_DISABLE_PCI; |
| } |
| size += copy_len; |
| max_out_size -= copy_len; |
| |
| /* Append a separator */ |
| copy_len = strlen(SEPARATOR); |
| memcpy(out + size, SEPARATOR, copy_len); |
| size += copy_len; |
| max_out_size -= copy_len; |
| |
| /* Copy_Len over the second input */ |
| copy_len = MIN(size2, max_out_size); |
| memcpy(out + size, data2, copy_len); |
| size += copy_len; |
| max_out_size -= copy_len; |
| |
| return size; |
| } |
| |
| |
| static GString *generic_fuzz_cmdline(FuzzTarget *t) |
| { |
| GString *cmd_line = g_string_new(TARGET_NAME); |
| if (!getenv("QEMU_FUZZ_ARGS")) { |
| usage(); |
| } |
| g_string_append_printf(cmd_line, " -display none \ |
| -machine accel=qtest, \ |
| -m 512M %s ", getenv("QEMU_FUZZ_ARGS")); |
| return cmd_line; |
| } |
| |
| static GString *generic_fuzz_predefined_config_cmdline(FuzzTarget *t) |
| { |
| gchar *args; |
| const generic_fuzz_config *config; |
| g_assert(t->opaque); |
| |
| config = t->opaque; |
| setenv("QEMU_AVOID_DOUBLE_FETCH", "1", 1); |
| if (config->argfunc) { |
| args = config->argfunc(); |
| setenv("QEMU_FUZZ_ARGS", args, 1); |
| g_free(args); |
| } else { |
| g_assert_nonnull(config->args); |
| setenv("QEMU_FUZZ_ARGS", config->args, 1); |
| } |
| setenv("QEMU_FUZZ_OBJECTS", config->objects, 1); |
| return generic_fuzz_cmdline(t); |
| } |
| |
| static void register_generic_fuzz_targets(void) |
| { |
| fuzz_add_target(&(FuzzTarget){ |
| .name = "generic-fuzz", |
| .description = "Fuzz based on any qemu command-line args. ", |
| .get_init_cmdline = generic_fuzz_cmdline, |
| .pre_fuzz = generic_pre_fuzz, |
| .fuzz = generic_fuzz, |
| .crossover = generic_fuzz_crossover |
| }); |
| |
| GString *name; |
| const generic_fuzz_config *config; |
| |
| for (int i = 0; |
| i < sizeof(predefined_configs) / sizeof(generic_fuzz_config); |
| i++) { |
| config = predefined_configs + i; |
| name = g_string_new("generic-fuzz"); |
| g_string_append_printf(name, "-%s", config->name); |
| fuzz_add_target(&(FuzzTarget){ |
| .name = name->str, |
| .description = "Predefined generic-fuzz config.", |
| .get_init_cmdline = generic_fuzz_predefined_config_cmdline, |
| .pre_fuzz = generic_pre_fuzz, |
| .fuzz = generic_fuzz, |
| .crossover = generic_fuzz_crossover, |
| .opaque = (void *)config |
| }); |
| } |
| } |
| |
| fuzz_target_init(register_generic_fuzz_targets); |
