MSP430: conditional_jump! macro initialises new_true to true, emitting a spurious jump

Version and Platform (required):

• Binary Ninja Version: 5.0.7648
• Edition: Non-Commercial
• OS: Ubuntu
• OS Version: 24.04
• CPU Architecture: x64

Bug Description:
On MSP430, a conditional jump whose target is in a different basic block lifts as an LLIL_IF followed by a spurious LLIL_JUMP_TO, rather than LLIL_IF with a resolved goto label.

The target block is then never lifted: none of its instructions appear in the function's LLIL, and HLIL renders the region as while (true) /* nop */ with the code silently missing.

Conditional jumps whose target is inside the current basic block (a self-loop) are unaffected. Unconditional jmp and br are unaffected in both directions.

Steps To Reproduce:
printf '\x3b\x40\x02\x24\x0b\x8f\x7b\x90\x21\x00\x01\x28\x0b\x43\x0f\x4b\x30\x41' > jmp_repro.bin in a terminal or open jmp_repro.bin attached and look at sub_0 (create a function at 0 if sub_0 does not exist).

Expected Behavior:
LLIL_IF with the true branch resolved to a goto label at 0xe, and the block at 0xe lifted.

In pseudo C, the function sub_0 should be

int16_t sub_0(int16_t arg1) {
  int16_t result = 0x2402-arg1;
  
  if (result < 0x21) {
     return result;
  }
  return 0;
}

Screenshots/Video Recording:

Binary:
jmp_repro.zip

Suspected cause (hypothesis, not verified by testing a patched build):
In the conditional_jump! macro in arch/msp430/src/lift.rs, new_true is initialised to true while new_false is initialised to false:

let mut new_true = true;
let mut new_false = false;

The unwrap_or_else closure sets new_true = true, which it already is. So when label_for_address succeeds, new_true remains true and the following block still executes:

if new_true {
    $il.mark_label(&mut true_label);
    $il.jump($il.const_ptr(true_addr)).append();
}

This would append a jump even though if_expr already targeted the resolved label — which matches the observed LLIL_JUMP_TO. The false path, correctly initialised, behaves as expected.

The initialisation is still present in dev as of today.

Suggested fix: let mut new_true = false;

Additional Information:

An ArchitectureHook that omits the new_true block and emits only il.if_expr with the resolved labels produces correct LLIL and HLIL on the reproducer above, and on larger MSP430 binaries.

Start in arch/msp430/src/lift.rs at the conditional_jump! macro and inspect how new_true and new_false control label resolution and appended jumps. Reproduce with jmp_repro.bin and inspect sub_0's LLIL and HLIL. Done means the true branch resolves to a goto label at 0xe, the spurious LLIL_JUMP_TO is absent, and the block at 0xe is lifted.