/* american fuzzy lop++ - high-performance binary-only instrumentation ------------------------------------------------------------------- Originally written by Andrew Griffiths and Michal Zalewski TCG instrumentation and block chaining support by Andrea Biondo QEMU 3.1.1 port, TCG thread-safety, CompareCoverage and NeverZero counters by Andrea Fioraldi Copyright 2015, 2016, 2017 Google Inc. All rights reserved. Copyright 2019-2020 AFLplusplus Project. All rights reserved. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0 This code is a shim patched into the separately-distributed source code of QEMU 3.1.0. It leverages the built-in QEMU tracing functionality to implement AFL-style instrumentation and to take care of the remaining parts of the AFL fork server logic. The resulting QEMU binary is essentially a standalone instrumentation tool; for an example of how to leverage it for other purposes, you can have a look at afl-showmap.c. */ #include "afl-qemu-common.h" #include "tcg.h" #include "tcg-op.h" #if TCG_TARGET_REG_BITS == 64 # define _DEFAULT_MO MO_64 #else # define _DEFAULT_MO MO_32 #endif static void afl_gen_compcov(target_ulong cur_loc, TCGv arg1, TCGv arg2, TCGMemOp ot, int is_imm) { if (cur_loc > afl_end_code || cur_loc < afl_start_code) return; if (__afl_cmp_map) { cur_loc = (cur_loc >> 4) ^ (cur_loc << 8); cur_loc &= CMP_MAP_W - 1; TCGv cur_loc_v = tcg_const_tl(cur_loc); switch (ot & MO_SIZE) { case MO_64: gen_helper_afl_cmplog_64(cur_loc_v, arg1, arg2); break; case MO_32: gen_helper_afl_cmplog_32(cur_loc_v, arg1, arg2); break; case MO_16: gen_helper_afl_cmplog_16(cur_loc_v, arg1, arg2); break; case MO_8: gen_helper_afl_cmplog_8(cur_loc_v, arg1, arg2); break; default: break; } tcg_temp_free(cur_loc_v); } else if (afl_compcov_level) { if (!is_imm && afl_compcov_level < 2) return; cur_loc = (cur_loc >> 4) ^ (cur_loc << 8); cur_loc &= MAP_SIZE - 7; TCGv cur_loc_v = tcg_const_tl(cur_loc); if (cur_loc >= afl_inst_rms) return; switch (ot & MO_SIZE) { case MO_64: gen_helper_afl_compcov_64(cur_loc_v, arg1, arg2); break; case MO_32: gen_helper_afl_compcov_32(cur_loc_v, arg1, arg2); break; case MO_16: gen_helper_afl_compcov_16(cur_loc_v, arg1, arg2); break; default: break; } tcg_temp_free(cur_loc_v); } } /* Routines for debug */ /* static void log_x86_saved_gpr(void) { static const char reg_names[CPU_NB_REGS][4] = { #ifdef TARGET_X86_64 [R_EAX] = "rax", [R_EBX] = "rbx", [R_ECX] = "rcx", [R_EDX] = "rdx", [R_ESI] = "rsi", [R_EDI] = "rdi", [R_EBP] = "rbp", [R_ESP] = "rsp", [8] = "r8", [9] = "r9", [10] = "r10", [11] = "r11", [12] = "r12", [13] = "r13", [14] = "r14", [15] = "r15", #else [R_EAX] = "eax", [R_EBX] = "ebx", [R_ECX] = "ecx", [R_EDX] = "edx", [R_ESI] = "esi", [R_EDI] = "edi", [R_EBP] = "ebp", [R_ESP] = "esp", #endif }; int i; for (i = 0; i < CPU_NB_REGS; ++i) { fprintf(stderr, "%s = %lx\n", reg_names[i], persistent_saved_gpr[i]); } } static void log_x86_sp_content(void) { fprintf(stderr, ">> SP = %lx -> %lx\n", persistent_saved_gpr[R_ESP], *(unsigned long*)persistent_saved_gpr[R_ESP]); }*/ static void callback_to_persistent_hook(void) { afl_persistent_hook_ptr(persistent_saved_gpr, guest_base); } static void gpr_saving(TCGv *cpu_regs, int regs_num) { int i; TCGv_ptr gpr_sv; TCGv_ptr first_pass_ptr = tcg_const_ptr(&persistent_first_pass); TCGv first_pass = tcg_temp_local_new(); TCGv one = tcg_const_tl(1); tcg_gen_ld8u_tl(first_pass, first_pass_ptr, 0); TCGLabel *lbl_restore_gpr = gen_new_label(); tcg_gen_brcond_tl(TCG_COND_NE, first_pass, one, lbl_restore_gpr); // save GPR registers for (i = 0; i < regs_num; ++i) { gpr_sv = tcg_const_ptr(&persistent_saved_gpr[i]); tcg_gen_st_tl(cpu_regs[i], gpr_sv, 0); tcg_temp_free_ptr(gpr_sv); } gen_set_label(lbl_restore_gpr); afl_gen_tcg_plain_call(&afl_persistent_loop); if (afl_persistent_hook_ptr) afl_gen_tcg_plain_call(callback_to_persistent_hook); // restore GPR registers for (i = 0; i < regs_num; ++i) { gpr_sv = tcg_const_ptr(&persistent_saved_gpr[i]); tcg_gen_ld_tl(cpu_regs[i], gpr_sv, 0); tcg_temp_free_ptr(gpr_sv); } tcg_temp_free_ptr(first_pass_ptr); tcg_temp_free(first_pass); tcg_temp_free(one); } static void restore_state_for_persistent(TCGv *cpu_regs, int regs_num, int sp) { if (persistent_save_gpr) { gpr_saving(cpu_regs, regs_num); } else if (afl_persistent_ret_addr == 0) { TCGv_ptr stack_off_ptr = tcg_const_ptr(&persistent_stack_offset); TCGv stack_off = tcg_temp_new(); tcg_gen_ld_tl(stack_off, stack_off_ptr, 0); tcg_gen_sub_tl(cpu_regs[sp], cpu_regs[sp], stack_off); tcg_temp_free(stack_off); } } #define AFL_QEMU_TARGET_I386_SNIPPET \ if (is_persistent) { \ \ if (s->pc == afl_persistent_addr) { \ \ restore_state_for_persistent(cpu_regs, AFL_REGS_NUM, R_ESP); \ /*afl_gen_tcg_plain_call(log_x86_saved_gpr); \ afl_gen_tcg_plain_call(log_x86_sp_content);*/ \ \ if (afl_persistent_ret_addr == 0) { \ \ TCGv paddr = tcg_const_tl(afl_persistent_addr); \ tcg_gen_qemu_st_tl(paddr, cpu_regs[R_ESP], persisent_retaddr_offset, \ _DEFAULT_MO); \ tcg_temp_free(paddr); \ \ } \ \ if (!persistent_save_gpr) afl_gen_tcg_plain_call(&afl_persistent_loop); \ /*afl_gen_tcg_plain_call(log_x86_sp_content);*/ \ \ } else if (afl_persistent_ret_addr && s->pc == afl_persistent_ret_addr) { \ \ gen_jmp_im(s, afl_persistent_addr); \ gen_eob(s); \ \ } \ \ } // SP = 13, LINK = 14 #define AFL_QEMU_TARGET_ARM_SNIPPET \ if (is_persistent) { \ \ if (dc->pc == afl_persistent_addr) { \ \ if (persistent_save_gpr) gpr_saving(cpu_R, AFL_REGS_NUM); \ \ if (afl_persistent_ret_addr == 0) { \ \ tcg_gen_movi_tl(cpu_R[14], afl_persistent_addr); \ \ } \ \ if (!persistent_save_gpr) afl_gen_tcg_plain_call(&afl_persistent_loop); \ \ } else if (afl_persistent_ret_addr && dc->pc == afl_persistent_ret_addr) { \ \ gen_bx_im(dc, afl_persistent_addr); \ \ } \ \ } // SP = 31, LINK = 30 #define AFL_QEMU_TARGET_ARM64_SNIPPET \ if (is_persistent) { \ \ if (s->pc == afl_persistent_addr) { \ \ if (persistent_save_gpr) gpr_saving(cpu_X, AFL_REGS_NUM); \ \ if (afl_persistent_ret_addr == 0) { \ \ tcg_gen_movi_tl(cpu_X[30], afl_persistent_addr); \ \ } \ \ if (!persistent_save_gpr) afl_gen_tcg_plain_call(&afl_persistent_loop); \ \ } else if (afl_persistent_ret_addr && s->pc == afl_persistent_ret_addr) { \ \ gen_goto_tb(s, 0, afl_persistent_addr); \ \ } \ \ }