[MSP430] Minor fixes/improvements for assembler/disassembler

* Teach AsmParser to recognize @rn in distination operand as 0(rn).
* Do not allow Disassembler decoding instructions that have size more
  than a number of input bytes.
* Fix UB in MSP430MCCodeEmitter.

Patch by Kristina Bessonova!

Differential Revision: https://reviews.llvm.org/D56547

llvm-svn: 350903

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Target/MSP430/Disassembler/MSP430Disassembler.cpp b/llvm/lib/Target/MSP430/Disassembler/MSP430Disassembler.cpp
index 2a66b4ed7f2..e5da130f9bb 100644
--- a/llvm/lib/Target/MSP430/Disassembler/MSP430Disassembler.cpp
+++ b/llvm/lib/Target/MSP430/Disassembler/MSP430Disassembler.cpp
@@ -249,6 +249,10 @@ DecodeStatus MSP430Disassembler::getInstructionI(MCInst &MI, uint64_t &Size,
   case amSymbolic:
   case amImmediate:
   case amAbsolute:
+    if (Bytes.size() < (Words + 1) * 2) {
+      Size = 2;
+      return DecodeStatus::Fail;
+    }
     Insn |= (uint64_t)support::endian::read16le(Bytes.data() + 2) << 16;
     ++Words;
     break;
@@ -259,6 +263,10 @@ DecodeStatus MSP430Disassembler::getInstructionI(MCInst &MI, uint64_t &Size,
   case amIndexed:
   case amSymbolic:
   case amAbsolute:
+    if (Bytes.size() < (Words + 1) * 2) {
+      Size = 2;
+      return DecodeStatus::Fail;
+    }
     Insn |= (uint64_t)support::endian::read16le(Bytes.data() + Words * 2)
         << (Words * 16);
     ++Words;
@@ -296,6 +304,10 @@ DecodeStatus MSP430Disassembler::getInstructionII(MCInst &MI, uint64_t &Size,
   case amSymbolic:
   case amImmediate:
   case amAbsolute:
+    if (Bytes.size() < (Words + 1) * 2) {
+      Size = 2;
+      return DecodeStatus::Fail;
+    }
     Insn |= (uint64_t)support::endian::read16le(Bytes.data() + 2) << 16;
     ++Words;
     break;