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[mips][microMIPS] Fix an invalid read for lwm32 and reserved reglist values.
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Authored by dsanders on Sep 18 2015, 6:39 AM.

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rGdf19a5e60523: [mips][microMIPS] Fix an invalid read for lwm32 and reserved reglist values.
rL247990: [mips][microMIPS] Fix an invalid read for lwm32 and reserved reglist values.

Summary

Some values of 'reglist' are reserved and cause the disassembler to read past
the end of the Regs array. Treat lwm32's containing reserved values as invalid
instructions.

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dsanders updated this revision to Diff 35078.Sep 18 2015, 6:39 AM

dsanders retitled this revision from to [mips][microMIPS] Fix an invalid read for lwm32 and reserved reglist values..

dsanders updated this object.

dsanders added a reviewer: zoran.jovanovic.

dsanders added a subscriber: llvm-commits.

LGTM.

This revision is now accepted and ready to land.Sep 18 2015, 7:05 AM

dsanders closed this revision.Sep 18 2015, 7:22 AM

Revision Contents

Path

Size

lib/

Target/

Mips/

Disassembler/

MipsDisassembler.cpp

6 lines

test/

MC/

Disassembler/

Mips/

micromips32r3/

invalid.txt

4 lines

Diff 35078

lib/Target/Mips/Disassembler/MipsDisassembler.cpp

Show First 20 Lines • Show All 1,913 Lines • ▼ Show 20 Lines	static DecodeStatus DecodeRegListOperand(MCInst &Inst,
unsigned Insn,		unsigned Insn,
uint64_t Address,		uint64_t Address,
const void *Decoder) {		const void *Decoder) {
unsigned Regs[] = {Mips::S0, Mips::S1, Mips::S2, Mips::S3, Mips::S4, Mips::S5,		unsigned Regs[] = {Mips::S0, Mips::S1, Mips::S2, Mips::S3, Mips::S4, Mips::S5,
Mips::S6, Mips::S7, Mips::FP};		Mips::S6, Mips::S7, Mips::FP};
unsigned RegNum;		unsigned RegNum;

unsigned RegLst = fieldFromInstruction(Insn, 21, 5);		unsigned RegLst = fieldFromInstruction(Insn, 21, 5);

// Empty register lists are not allowed.		// Empty register lists are not allowed.
if (RegLst == 0)		if (RegLst == 0)
return MCDisassembler::Fail;		return MCDisassembler::Fail;

RegNum = RegLst & 0xf;		RegNum = RegLst & 0xf;

		// RegLst values 10-15, and 26-31 are reserved.
		if (RegNum > 9)
		return MCDisassembler::Fail;

for (unsigned i = 0; i < RegNum; i++)		for (unsigned i = 0; i < RegNum; i++)
Inst.addOperand(MCOperand::createReg(Regs[i]));		Inst.addOperand(MCOperand::createReg(Regs[i]));

if (RegLst & 0x10)		if (RegLst & 0x10)
Inst.addOperand(MCOperand::createReg(Mips::RA));		Inst.addOperand(MCOperand::createReg(Mips::RA));

return MCDisassembler::Success;		return MCDisassembler::Success;
}		}
▲ Show 20 Lines • Show All 66 Lines • Show Last 20 Lines

test/MC/Disassembler/Mips/micromips32r3/

This directory was added.

test/MC/Disassembler/Mips/micromips32r3/invalid.txt

This file was added.

				# RUN: llvm-mc --disassemble %s -triple=mips-unknown-linux -mattr=micromips \
				# RUN: 2>&1 \| FileCheck %s

				0x21 0xe2 0x5c 0x71 # CHECK: :[[@LINE]]:1: warning: invalid instruction encoding