Function find_jump_table

python/examples/jump_table.py:28–83

(bv, addr)

def find_jump_table(bv, addr):
	for block in bv.get_basic_blocks_at(addr):
		func = block.function
		arch = func.arch
		addrsize = arch.address_size

		# Grab the instruction tokens so that we can look for the table's starting address
		tokens, length = arch.get_instruction_text(bv.read(addr, 16), addr)

		# Look for the next jump instruction, which may be the current instruction. Some jump tables will
		# compute the address first then jump to the computed address as a separate instruction.
		jump_addr = addr
		while jump_addr < block.end:
			info = arch.get_instruction_info(bv.read(jump_addr, 16), jump_addr)
			if len(info.branches) != 0:
				break
			jump_addr += info.length
		if jump_addr >= block.end:
			print("Unable to find jump after instruction 0x%x" % addr)
			continue
		print("Jump at 0x%x" % jump_addr)

		# Collect the branch targets for any tables referenced by the clicked instruction
		branches = []
		for token in tokens:
			if InstructionTextTokenType(
			  token.type
			) == InstructionTextTokenType.PossibleAddressToken:  # Table addresses will be a "possible address" token
				tbl = token.value
				print("Found possible table at 0x%x" % tbl)
				i = 0
				while True:
					# Read the next pointer from the table
					data = bv.read(tbl + (i*addrsize), addrsize)
					if len(data) == addrsize:
						if addrsize == 4:
							ptr = struct.unpack("<I", data)[0]
						else:
							ptr = struct.unpack("<Q", data)[0]

						# If the pointer is within the binary, add it as a destination and continue
						# to the next entry
						if (ptr >= bv.start) and (ptr < bv.end):
							print("Found destination 0x%x" % ptr)
							branches.append((arch, ptr))
						else:
							# Once a value that is not a pointer is encountered, the jump table is ended
							break
					else:
						# Reading invalid memory
						break

					i += 1

		# Set the indirect branch targets on the jump instruction to be the list of targets discovered
		func.set_user_indirect_branches(jump_addr, branches)