[llvm] r370540 - [MC] Avoid crashes from improperly nested or wrong target .seh_handlerdata directives

[Reid Kleckner via llvm-commits]

Author: rnk
Date: Fri Aug 30 15:25:55 2019
New Revision: 370540

URL: http://llvm.org/viewvc/llvm-project?rev=370540&view=rev
Log:
[MC] Avoid crashes from improperly nested or wrong target .seh_handlerdata directives

Modified:
    llvm/trunk/lib/MC/MCAsmStreamer.cpp
    llvm/trunk/lib/MC/MCParser/COFFAsmParser.cpp
    llvm/trunk/lib/Target/X86/MCTargetDesc/X86WinCOFFStreamer.cpp
    llvm/trunk/test/MC/AsmParser/seh-directive-errors.s

Modified: llvm/trunk/lib/MC/MCAsmStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCAsmStreamer.cpp?rev=370540&r1=370539&r2=370540&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCAsmStreamer.cpp (original)
+++ llvm/trunk/lib/MC/MCAsmStreamer.cpp Fri Aug 30 15:25:55 2019
@@ -1748,6 +1748,12 @@ void MCAsmStreamer::EmitWinEHHandlerData
   // We only do this so the section switch that terminates the handler
   // data block is visible.
   WinEH::FrameInfo *CurFrame = getCurrentWinFrameInfo();
+
+  // Do nothing if no frame is open. MCStreamer should've already reported an
+  // error.
+  if (!CurFrame)
+    return;
+
   MCSection *TextSec = &CurFrame->Function->getSection();
   MCSection *XData = getAssociatedXDataSection(TextSec);
   SwitchSectionNoChange(XData);

Modified: llvm/trunk/lib/MC/MCParser/COFFAsmParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCParser/COFFAsmParser.cpp?rev=370540&r1=370539&r2=370540&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCParser/COFFAsmParser.cpp (original)
+++ llvm/trunk/lib/MC/MCParser/COFFAsmParser.cpp Fri Aug 30 15:25:55 2019
@@ -69,6 +69,7 @@ class COFFAsmParser : public MCAsmParser
     addDirectiveHandler<&COFFAsmParser::ParseDirectiveSecIdx>(".secidx");
     addDirectiveHandler<&COFFAsmParser::ParseDirectiveLinkOnce>(".linkonce");
     addDirectiveHandler<&COFFAsmParser::ParseDirectiveRVA>(".rva");
+    addDirectiveHandler<&COFFAsmParser::ParseDirectiveSymbolAttribute>(".weak");
 
     // Win64 EH directives.
     addDirectiveHandler<&COFFAsmParser::ParseSEHDirectiveStartProc>(
@@ -87,7 +88,6 @@ class COFFAsmParser : public MCAsmParser
                                                              ".seh_stackalloc");
     addDirectiveHandler<&COFFAsmParser::ParseSEHDirectiveEndProlog>(
                                                             ".seh_endprologue");
-    addDirectiveHandler<&COFFAsmParser::ParseDirectiveSymbolAttribute>(".weak");
   }
 
   bool ParseSectionDirectiveText(StringRef, SMLoc) {

Modified: llvm/trunk/lib/Target/X86/MCTargetDesc/X86WinCOFFStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/MCTargetDesc/X86WinCOFFStreamer.cpp?rev=370540&r1=370539&r2=370540&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/MCTargetDesc/X86WinCOFFStreamer.cpp (original)
+++ llvm/trunk/lib/Target/X86/MCTargetDesc/X86WinCOFFStreamer.cpp Fri Aug 30 15:25:55 2019
@@ -35,8 +35,9 @@ void X86WinCOFFStreamer::EmitWinEHHandle
   MCStreamer::EmitWinEHHandlerData(Loc);
 
   // We have to emit the unwind info now, because this directive
-  // actually switches to the .xdata section!
-  EHStreamer.EmitUnwindInfo(*this, getCurrentWinFrameInfo());
+  // actually switches to the .xdata section.
+  if (WinEH::FrameInfo *CurFrame = getCurrentWinFrameInfo())
+    EHStreamer.EmitUnwindInfo(*this, CurFrame);
 }
 
 void X86WinCOFFStreamer::EmitWindowsUnwindTables() {

Modified: llvm/trunk/test/MC/AsmParser/seh-directive-errors.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/AsmParser/seh-directive-errors.s?rev=370540&r1=370539&r2=370540&view=diff
==============================================================================
--- llvm/trunk/test/MC/AsmParser/seh-directive-errors.s (original)
+++ llvm/trunk/test/MC/AsmParser/seh-directive-errors.s Fri Aug 30 15:25:55 2019
@@ -1,6 +1,10 @@
 # RUN: not llvm-mc -triple x86_64-windows-msvc %s -filetype=obj -o /dev/null 2>&1 | FileCheck %s --implicit-check-not=error:
+# RUN: not llvm-mc -triple x86_64-windows-msvc %s -o /dev/null 2>&1 | FileCheck %s --implicit-check-not=error:
 	.text
 
+# CHECK: error: .seh_ directive must appear within an active frame
+	.seh_handlerdata
+
 	.seh_pushreg %rsi
 	# CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: .seh_ directive must appear within an active frame