X86: validate 'int' instruction

The int instruction takes as an operand an 8-bit immediate value.  Validate that
the input is valid rather than silently truncating the value.

llvm-svn: 225941

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
index bb738231baa..28824488a71 100644
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -684,6 +684,7 @@ private:
   bool ParseDirectiveWord(unsigned Size, SMLoc L);
   bool ParseDirectiveCode(StringRef IDVal, SMLoc L);
 
+  bool validateInstruction(MCInst &Inst, const OperandVector &Ops);
   bool processInstruction(MCInst &Inst, const OperandVector &Ops);
 
   /// Wrapper around MCStreamer::EmitInstruction(). Possibly adds
@@ -2272,6 +2273,20 @@ static bool convert64i32to64ri8(MCInst &Inst, unsigned Opcode,
   return convertToSExti8(Inst, Opcode, X86::RAX, isCmp);
 }
 
+bool X86AsmParser::validateInstruction(MCInst &Inst, const OperandVector &Ops) {
+  switch (Inst.getOpcode()) {
+  default: return true;
+  case X86::INT:
+    assert(Inst.getOperand(0).isImm() && "expected immediate");
+    if (Inst.getOperand(0).getImm() > 255) {
+      Error(Ops[1]->getStartLoc(), "interrupt vector must be in range [0-255]");
+      return false;
+    }
+    return true;
+  }
+  llvm_unreachable("handle the instruction appropriately");
+}
+
 bool X86AsmParser::processInstruction(MCInst &Inst, const OperandVector &Ops) {
   switch (Inst.getOpcode()) {
   default: return false;
@@ -2434,6 +2449,9 @@ bool X86AsmParser::MatchAndEmitATTInstruction(SMLoc IDLoc, unsigned &Opcode,
                                isParsingIntelSyntax())) {
   default: llvm_unreachable("Unexpected match result!");
   case Match_Success:
+    if (!validateInstruction(Inst, Operands))
+      return true;
+
     // Some instructions need post-processing to, for example, tweak which
     // encoding is selected. Loop on it while changes happen so the
     // individual transformations can chain off each other.
@@ -2677,6 +2695,9 @@ bool X86AsmParser::MatchAndEmitIntelInstruction(SMLoc IDLoc, unsigned &Opcode,
   unsigned NumSuccessfulMatches =
       std::count(std::begin(Match), std::end(Match), Match_Success);
   if (NumSuccessfulMatches == 1) {
+    if (!validateInstruction(Inst, Operands))
+      return true;
+
     // Some instructions need post-processing to, for example, tweak which
     // encoding is selected. Loop on it while changes happen so the individual
     // transformations can chain off each other.