8271486: [lworld] Memory corruption due to out of bound access in MacroAssembler::move_helper

[TobiHartmann]

While debugging weird crashes that only showed up when merging current mainline with lworld, I've noticed that we are writing outside of the reg_state array in MacroAssembler::move_helper because from->value() is -1 (OptoReg::BAD_REG):

valhalla/src/hotspot/cpu/x86/macroAssembler_x86.cpp

Lines 5794 to 5797 in 3c399d9

	// Update register states
	reg_state[from->value()] = reg_writable;
	reg_state[to->value()] = reg_written;
	return true;

The register is invalid because it belongs to the second half of a T_LONG or T_DOUBLE argument in the calling convention and should simply be ignored. I've also added asserts to catch similar issues in the future.

Thanks,
Tobias

---

Progress

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Issue

• JDK-8271486: [lworld] Memory corruption due to out of bound access in MacroAssembler::move_helper

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8271486: [lworld] Memory corruption due to out of bound access in MacroAssembler::move_helper

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Webrevs

• 00: Full (dac9de96)

[TobiHartmann]

/integrate

[openjdk]

Going to push as commit 233d7bb.

[openjdk]

@TobiHartmann Pushed as commit 233d7bb.

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