fixed speculative execution which was broken

pull/1/head
xtremegamer1 2 years ago
parent 907bbb32aa
commit 4767c79d42

@ -172,6 +172,7 @@ void emu_t::extract_branch_data() {
br1 += m_vm->m_module_base;
br2 += m_vm->m_module_base;
// We need to handle the case that the jump points to another jump
auto br1_legit = legit_branch(*cc_blk, br1);
auto br2_legit = legit_branch(*cc_blk, br2);
std::printf("> br1 legit: %d, br2 legit: %d\n", br1_legit, br2_legit);
@ -269,19 +270,10 @@ bool emu_t::branch_pred_spec_exec(uc_engine* uc, uint64_t address,
}
if (instr.mnemonic == ZYDIS_MNEMONIC_INVALID) return false;
uc_context* ctx;
uct_context_alloc(uc, &ctx);
uc_context_save(uc, ctx);
// if this is the first instruction of this handler then save the stack...
if (!obj->cc_trace.m_instrs.size()) {
obj->cc_trace.m_vip = obj->cc_blk->m_vm.vip;
obj->cc_trace.m_vsp = obj->cc_blk->m_vm.vsp;
obj->cc_trace.m_stack = new std::uint8_t[STACK_SIZE]; g_new_delete_tracker++;
uc_mem_read(uc, STACK_BASE, obj->cc_trace.m_stack, STACK_SIZE);
}
obj->cc_trace.m_instrs.push_back({instr, ctx});
// RET or JMP REG means the end of a vm handler...
@ -292,7 +284,7 @@ bool emu_t::branch_pred_spec_exec(uc_engine* uc, uint64_t address,
// makes it easier for profiles to be correct...
vm::instrs::deobfuscate(obj->cc_trace);
// find the last MOV REG, DWORD PTR [VIP] in the instruction stream, then
/* // find the last MOV REG, DWORD PTR [VIP] in the instruction stream, then
// remove any instructions from this instruction to the JMP/RET...
const auto rva_fetch = std::find_if(
obj->cc_trace.m_instrs.rbegin(), obj->cc_trace.m_instrs.rend(),
@ -313,7 +305,7 @@ bool emu_t::branch_pred_spec_exec(uc_engine* uc, uint64_t address,
}
obj->cc_trace.m_instrs.erase((rva_fetch + 1).base(),
obj->cc_trace.m_instrs.end());
}
} */
const auto vinstr = vm::instrs::determine(obj->cc_trace);
@ -323,7 +315,6 @@ bool emu_t::branch_pred_spec_exec(uc_engine* uc, uint64_t address,
uct_context_free(instr.m_cpu);
});
delete[] obj->cc_trace.m_stack; if (obj->cc_trace.m_stack) g_new_delete_tracker--;
obj->cc_trace.m_instrs.clear();
if (vinstr.mnemonic != vm::instrs::mnemonic_t::jmp) {
@ -566,6 +557,10 @@ bool emu_t::legit_branch(vm::instrs::vblk_t& vblk, std::uintptr_t branch_addr) {
uc_reg_read(uc, vm::instrs::reg_map[vblk.m_vm.vsp], &vsp);
uc_mem_write(uc, vsp, &branch_addr, sizeof branch_addr);
// reset vsp and vip to their pre-jmp status in the current code trace
// this will be reset when the jmp instruction is emulated again
cc_trace.m_vsp = cc_blk->m_vm.vsp, cc_trace.m_vip = cc_blk->m_vm.vip;
m_sreg_cnt = 0u;
uc_emu_start(uc, rip, 0ull, 0ull, 0ull);
@ -606,31 +601,37 @@ std::optional<std::pair<std::uintptr_t, std::uintptr_t>> emu_t::could_have_jcc(
return v.mnemonic == vm::instrs::mnemonic_t::lconst && v.imm.size == 64;
};
const auto lconst1 =
std::find_if(vinstrs.rbegin(), vinstrs.rend(), lconst64_chk);
if (lconst1 == vinstrs.rend()) return {};
const auto lconst2 = std::find_if(lconst1 + 1, vinstrs.rend(), lconst64_chk);
static const auto valid_mem = [=](uintptr_t loc)
{
// check to see if the imm val is inside of the image...
if (loc > m_vm->m_image_base + m_vm->m_image_size ||
loc < m_vm->m_image_base ||
loc > m_vm->m_image_base + m_vm->m_image_size ||
loc < m_vm->m_image_base)
return false;
// check to see if the imm's points to something inside of an executable
// section...
if (!vm::utils::scn::executable(
m_vm->m_module_base,
(loc - m_vm->m_image_base) + m_vm->m_module_base))
return false;
return true;
};
auto lconst1 = vinstrs.rbegin();
do {
lconst1 =
std::find_if(lconst1 + 1, vinstrs.rend(), lconst64_chk);
if (lconst1 == vinstrs.rend()) return {};
} while (!valid_mem(lconst1->imm.val));
auto lconst2 = lconst1;
do {
lconst2 =
std::find_if(lconst2 + 1, vinstrs.rend(), lconst64_chk);
if (lconst2 == vinstrs.rend()) return {};
// check to see if the imm val is inside of the image...
if (lconst1->imm.val > m_vm->m_image_base + m_vm->m_image_size ||
lconst1->imm.val < m_vm->m_image_base ||
lconst2->imm.val > m_vm->m_image_base + m_vm->m_image_size ||
lconst2->imm.val < m_vm->m_image_base)
return {};
// check to see if the imm's points to something inside of an executable
// section...
if (!vm::utils::scn::executable(
m_vm->m_module_base,
(lconst1->imm.val - m_vm->m_image_base) + m_vm->m_module_base) ||
!vm::utils::scn::executable(
m_vm->m_module_base,
(lconst2->imm.val - m_vm->m_image_base) + m_vm->m_module_base))
return {};
} while (!valid_mem(lconst1->imm.val));
return {{lconst1->imm.val, lconst2->imm.val}};
}

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