From: Wei Liu Date: Thu, 8 Dec 2016 12:09:54 +0000 (+0000) Subject: tools/fuzz: introduce x86 instruction emulator target X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~3170 X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=c808475882ef852206affd1ed67776642b195aa5;p=xen.git tools/fuzz: introduce x86 instruction emulator target Instruction emulator fuzzing code is from code previous written by Andrew and George. Adapt it to llvm fuzzer and hook up the build system. Signed-off-by: Andrew Cooper Signed-off-by: George Dunlap Signed-off-by: Wei Liu Reviewed-by: Jan Beulich --- diff --git a/.gitignore b/.gitignore index a2f34a14cb..d507243b4d 100644 --- a/.gitignore +++ b/.gitignore @@ -145,6 +145,7 @@ tools/flask/utils/flask-loadpolicy tools/flask/utils/flask-setenforce tools/flask/utils/flask-set-bool tools/flask/utils/flask-label-pci +tools/fuzz/x86_instruction_emulator/x86_emulate* tools/helpers/_paths.h tools/helpers/init-xenstore-domain tools/helpers/xen-init-dom0 diff --git a/tools/fuzz/x86_instruction_emulator/Makefile b/tools/fuzz/x86_instruction_emulator/Makefile new file mode 100644 index 0000000000..a97f50781e --- /dev/null +++ b/tools/fuzz/x86_instruction_emulator/Makefile @@ -0,0 +1,36 @@ +XEN_ROOT=$(CURDIR)/../../.. +include $(XEN_ROOT)/tools/Rules.mk + +.PHONY: x86-instruction-emulator-fuzzer-all +ifeq ($(CONFIG_X86_64),y) +x86-instruction-emulator-fuzzer-all: x86-insn-emulator.a x86-insn-emulator-fuzzer.o +else +x86-instruction-emulator-fuzzer-all: +endif + +x86_emulate/x86_emulate.c x86_emulate/x86_emulate.h: + [ -L x86_emulate ] || ln -sf $(XEN_ROOT)/xen/arch/x86/x86_emulate . + +x86_emulate.c x86_emulate.h: %: + [ -L $* ] || ln -sf $(XEN_ROOT)/tools/tests/x86_emulator/$* + +CFLAGS += $(CFLAGS_xeninclude) + +x86_emulate.o: x86_emulate.c x86_emulate.h x86_emulate/x86_emulate.c x86_emulate/x86_emulate.h + +x86-insn-emulator.a: x86_emulate.o + $(AR) rc $@ $^ + +x86-insn-emulator-fuzzer.o: x86-insn-emulator-fuzzer.c + +# Common targets +.PHONY: all +all: x86-instruction-emulator-fuzzer-all + +.PHONY: distclean +distclean: clean + rm -f x86_emulate x86_emulate.c x86_emulate.h + +.PHONY: clean +clean: + rm -f *.a *.o diff --git a/tools/fuzz/x86_instruction_emulator/x86-insn-emulator-fuzzer.c b/tools/fuzz/x86_instruction_emulator/x86-insn-emulator-fuzzer.c new file mode 100644 index 0000000000..7d7f731677 --- /dev/null +++ b/tools/fuzz/x86_instruction_emulator/x86-insn-emulator-fuzzer.c @@ -0,0 +1,190 @@ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "x86_emulate.h" + +static unsigned char data[4096]; +static unsigned int data_index; +static unsigned int data_max; + +static int data_read(const char *why, void *dst, unsigned int bytes) +{ + unsigned int i; + + if ( data_index + bytes > data_max ) + return X86EMUL_EXCEPTION; + + memcpy(dst, data + data_index, bytes); + data_index += bytes; + + printf("%s: ", why); + for ( i = 0; i < bytes; i++ ) + printf(" %02x", *(unsigned char *)(dst + i)); + printf("\n"); + + return X86EMUL_OKAY; +} + +static int fuzz_read( + unsigned int seg, + unsigned long offset, + void *p_data, + unsigned int bytes, + struct x86_emulate_ctxt *ctxt) +{ + return data_read("read", p_data, bytes); +} + +static int fuzz_fetch( + unsigned int seg, + unsigned long offset, + void *p_data, + unsigned int bytes, + struct x86_emulate_ctxt *ctxt) +{ + return data_read("fetch", p_data, bytes); +} + +static int fuzz_write( + unsigned int seg, + unsigned long offset, + void *p_data, + unsigned int bytes, + struct x86_emulate_ctxt *ctxt) +{ + return X86EMUL_OKAY; +} + +static int fuzz_cmpxchg( + unsigned int seg, + unsigned long offset, + void *old, + void *new, + unsigned int bytes, + struct x86_emulate_ctxt *ctxt) +{ + return X86EMUL_OKAY; +} + +static struct x86_emulate_ops fuzz_emulops = { + .read = fuzz_read, + .insn_fetch = fuzz_fetch, + .write = fuzz_write, + .cmpxchg = fuzz_cmpxchg, + .cpuid = emul_test_cpuid, + .read_cr = emul_test_read_cr, + .get_fpu = emul_test_get_fpu, +}; + +#define CANONICALIZE(x) \ + do { \ + uint64_t _y = (x); \ + if ( _y & (1ULL << 47) ) \ + _y |= (~0ULL) << 48; \ + else \ + _y &= (1ULL << 48)-1; \ + printf("Canonicalized %" PRIx64 " to %" PRIx64 "\n", x, _y); \ + (x) = _y; \ + } while( 0 ) + +#define ADDR_SIZE_SHIFT 60 +#define ADDR_SIZE_64 (2ULL << ADDR_SIZE_SHIFT) +#define ADDR_SIZE_32 (1ULL << ADDR_SIZE_SHIFT) +#define ADDR_SIZE_16 (0) + +int LLVMFuzzerTestOneInput(const uint8_t *data_p, size_t size) +{ + bool stack_exec; + struct cpu_user_regs regs = {}; + struct x86_emulate_ctxt ctxt = { + .regs = ®s, + .addr_size = 8 * sizeof(void *), + .sp_size = 8 * sizeof(void *), + }; + unsigned int nr = 0; + int rc; + unsigned int x; + const uint8_t *p = data_p; + + stack_exec = emul_test_make_stack_executable(); + if ( !stack_exec ) + { + printf("Warning: Stack could not be made executable (%d).\n", errno); + return 1; + } + + /* Reset all global state variables */ + memset(data, 0, sizeof(data)); + data_index = 0; + data_max = 0; + + nr = size < sizeof(regs) ? size : sizeof(regs); + + memcpy(®s, p, nr); + p += sizeof(regs); + + if ( nr < size ) + { + memcpy(data, p, size - nr); + data_max = size - nr; + } + + ctxt.force_writeback = false; + + /* Zero 'private' fields */ + regs.error_code = 0; + regs.entry_vector = 0; + + /* Use the upper bits of regs.eip to determine addr_size */ + x = (regs.rip >> ADDR_SIZE_SHIFT) & 0x3; + if ( x == 3 ) + x = 2; + ctxt.addr_size = 16 << x; + printf("addr_size: %d\n", ctxt.addr_size); + + /* Use the upper bit of regs.rsp to determine sp_size (if appropriate) */ + if ( ctxt.addr_size == 64 ) + ctxt.sp_size = 64; + else + { + /* If addr_size isn't 64-bits, sp_size can only be 16 or 32 bits */ + x = (regs.rsp >> ADDR_SIZE_SHIFT) & 0x1; + ctxt.sp_size = 16 << x; + } + printf("sp_size: %d\n", ctxt.sp_size); + CANONICALIZE(regs.rip); + CANONICALIZE(regs.rsp); + CANONICALIZE(regs.rbp); + + /* Zero all segments for now */ + regs.cs = regs.ss = regs.es = regs.ds = regs.fs = regs.gs = 0; + + do { + rc = x86_emulate(&ctxt, &fuzz_emulops); + printf("Emulation result: %d\n", rc); + } while ( rc == X86EMUL_OKAY ); + + return 0; +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * indent-tabs-mode: nil + * End: + */