[DataLayout] Check StackNatural and FunctionPtr alignments.

[fhahn]

Summary

MaybeAlignment asserts that the passed in value is == 0 or a power of 2.

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=16272

[gchatelet]

LGTM. Thx!

[jfb]

Nice catch :)

llvm/lib/IR/DataLayout.cpp

323 ↗

(On Diff #213847)

?

[fhahn]

llvm/lib/IR/DataLayout.cpp

323 ↗

(On Diff #213847)

Woops, looks like I forgot to strip that one. I'll remove it before committing.

llvm/trunk/lib/IR/DataLayout.cpp

case 'n':  // Native integer types.
               "Zero width native integer type in datalayout string");
         LegalIntWidths.push_back(Width);
         if (Rest.empty())
           break;
         Split = split(Rest, ':');
       }
       break;
     case 'S': { // Stack natural alignment.
-      StackNaturalAlign = MaybeAlign(inBytes(getInt(Tok)));
+      uint64_t Alignment = inBytes(getInt(Tok));
+      if (Alignment != 0 && !llvm::isPowerOf2_64(Alignment))
+        report_fatal_error("Alignment is neither 0 nor a power of 2");
+      StackNaturalAlign = MaybeAlign(Alignment);
       break;
     }
     case 'F': {
       switch (Tok.front()) {
       case 'i':
         TheFunctionPtrAlignType = FunctionPtrAlignType::Independent;
         break;
       case 'n':
         TheFunctionPtrAlignType = FunctionPtrAlignType::MultipleOfFunctionAlign;
         break;
       default:
         report_fatal_error("Unknown function pointer alignment type in "
                            "datalayout string");
       }
       Tok = Tok.substr(1);
-      FunctionPtrAlign = MaybeAlign(inBytes(getInt(Tok)));
+      uint64_t Alignment = inBytes(getInt(Tok));
+      if (Alignment != 0 && !llvm::isPowerOf2_64(Alignment))
+        report_fatal_error("Alignment is neither 0 nor a power of 2");
+      FunctionPtrAlign = MaybeAlign(Alignment);
       break;
     }
     case 'P': { // Function address space.
       ProgramAddrSpace = getAddrSpace(Tok);
       break;
     }
     case 'A': { // Default stack/alloca address space.
       AllocaAddrSpace = getAddrSpace(Tok);

llvm/trunk/test/Assembler/datalayout-invalid-function-ptr-alignment.ll

+; RUN: not llvm-as %s 2>&1 | FileCheck %s
+
+; CHECK: LLVM ERROR: Alignment is neither 0 nor a power of 2
+
+target datalayout = "Fi24"

llvm/trunk/test/Assembler/datalayout-invalid-stack-natural-alignment.ll

+; RUN: not llvm-as %s 2>&1 | FileCheck %s
+
+; CHECK: LLVM ERROR: Alignment is neither 0 nor a power of 2
+
+target datalayout = "S24"

llvm/trunk/test/Bitcode/invalid-functionptr-align.ll

+; Bitcode with invalid function pointer alignment.
+
+; RUN: not llvm-dis %s.bc -o - 2>&1 | FileCheck %s
+
+CHECK: LLVM ERROR: Alignment is neither 0 nor a power of 2