From: Craig Topper <craig.topper@intel.com>
Date: Sun, 22 Oct 2017 04:32:30 +0000 (+0000)
Subject: [X86] Don't allow gather/scatter to disassembler if memory operand does not use a... 
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=158bc6474a5192bb42e8d03944ad0b689e6e2d56;p=platform%2Fupstream%2Fllvm.git

[X86] Don't allow gather/scatter to disassembler if memory operand does not use a SIB byte.

Fixes PR34998.

llvm-svn: 316282
---

diff --git a/llvm/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp b/llvm/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
index 6884f2a..e781c98 100644
--- a/llvm/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
+++ b/llvm/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
@@ -1723,6 +1723,10 @@ static int readOperands(struct InternalInstruction* insn) {
       if (readModRM(insn))
         return -1;
 
+      // Reject if SIB wasn't used.
+      if (insn->eaBase != EA_BASE_sib && insn->eaBase != EA_BASE_sib64)
+        return -1;
+
       // If sibIndex was set to SIB_INDEX_NONE, index offset is 4.
       if (insn->sibIndex == SIB_INDEX_NONE)
         insn->sibIndex = (SIBIndex)4;
diff --git a/llvm/test/MC/Disassembler/X86/gather-novsib.txt b/llvm/test/MC/Disassembler/X86/gather-novsib.txt
new file mode 100644
index 0000000..d14abc1
--- /dev/null
+++ b/llvm/test/MC/Disassembler/X86/gather-novsib.txt
@@ -0,0 +1,4 @@
+# RUN: llvm-mc --disassemble %s -triple=x86_64-apple-darwin9 2>&1 | grep "invalid instruction encoding"
+
+// This corresponds to a gather, but doesn't use a SIB byte.
+0xc4,0xe2,0xe9,0x92,0x08