[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.
Reviewers: zoran.jovanovic
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D12959
llvm-svn: 247990
diff --git a/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp b/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
index 4aa0afd..27eb399 100644
--- a/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
+++ b/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
@@ -1919,11 +1919,17 @@
unsigned RegNum;
unsigned RegLst = fieldFromInstruction(Insn, 21, 5);
+
// Empty register lists are not allowed.
if (RegLst == 0)
return MCDisassembler::Fail;
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++)
Inst.addOperand(MCOperand::createReg(Regs[i]));