[llvm] r349221 - [WebAssembly] Check if the section order is correct

Heejin Ahn via llvm-commits llvm-commits at lists.llvm.org
Fri Dec 14 16:58:12 PST 2018


Author: aheejin
Date: Fri Dec 14 16:58:12 2018
New Revision: 349221

URL: http://llvm.org/viewvc/llvm-project?rev=349221&view=rev
Log:
[WebAssembly] Check if the section order is correct

Summary:
This patch checks if the section order is correct when reading a wasm
object file in `WasmObjectFile` and converting YAML to wasm object in
yaml2wasm. (It is not possible to check when reading YAML because it is
handled exclusively by the YAML reader.)

This checks the ordering of all known sections (core sections + known
custom sections). This also adds section ID DataCount section that will
be scheduled to be added in near future.

Reviewers: sbc100

Subscribers: dschuff, mgorny, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D54924

Added:
    llvm/trunk/test/Object/Inputs/WASM/invalid-section-order.wasm
    llvm/trunk/test/Object/wasm-invalid-section-order.test
    llvm/trunk/test/ObjectYAML/wasm/invalid_section_order.yaml
Modified:
    llvm/trunk/include/llvm/BinaryFormat/Wasm.h
    llvm/trunk/include/llvm/Object/Wasm.h
    llvm/trunk/lib/Object/WasmObjectFile.cpp
    llvm/trunk/tools/yaml2obj/yaml2wasm.cpp

Modified: llvm/trunk/include/llvm/BinaryFormat/Wasm.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/BinaryFormat/Wasm.h?rev=349221&r1=349220&r2=349221&view=diff
==============================================================================
--- llvm/trunk/include/llvm/BinaryFormat/Wasm.h (original)
+++ llvm/trunk/include/llvm/BinaryFormat/Wasm.h Fri Dec 14 16:58:12 2018
@@ -188,19 +188,20 @@ struct WasmLinkingData {
 };
 
 enum : unsigned {
-  WASM_SEC_CUSTOM = 0,   // Custom / User-defined section
-  WASM_SEC_TYPE = 1,     // Function signature declarations
-  WASM_SEC_IMPORT = 2,   // Import declarations
-  WASM_SEC_FUNCTION = 3, // Function declarations
-  WASM_SEC_TABLE = 4,    // Indirect function table and other tables
-  WASM_SEC_MEMORY = 5,   // Memory attributes
-  WASM_SEC_GLOBAL = 6,   // Global declarations
-  WASM_SEC_EXPORT = 7,   // Exports
-  WASM_SEC_START = 8,    // Start function declaration
-  WASM_SEC_ELEM = 9,     // Elements section
-  WASM_SEC_CODE = 10,    // Function bodies (code)
-  WASM_SEC_DATA = 11,    // Data segments
-  WASM_SEC_EVENT = 13    // Event declarations
+  WASM_SEC_CUSTOM = 0,     // Custom / User-defined section
+  WASM_SEC_TYPE = 1,       // Function signature declarations
+  WASM_SEC_IMPORT = 2,     // Import declarations
+  WASM_SEC_FUNCTION = 3,   // Function declarations
+  WASM_SEC_TABLE = 4,      // Indirect function table and other tables
+  WASM_SEC_MEMORY = 5,     // Memory attributes
+  WASM_SEC_GLOBAL = 6,     // Global declarations
+  WASM_SEC_EXPORT = 7,     // Exports
+  WASM_SEC_START = 8,      // Start function declaration
+  WASM_SEC_ELEM = 9,       // Elements section
+  WASM_SEC_CODE = 10,      // Function bodies (code)
+  WASM_SEC_DATA = 11,      // Data segments
+  WASM_SEC_DATACOUNT = 12, // Data segment count
+  WASM_SEC_EVENT = 13      // Event declarations
 };
 
 // Type immediate encodings used in various contexts.

Modified: llvm/trunk/include/llvm/Object/Wasm.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Object/Wasm.h?rev=349221&r1=349220&r2=349221&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Object/Wasm.h (original)
+++ llvm/trunk/include/llvm/Object/Wasm.h Fri Dec 14 16:58:12 2018
@@ -283,6 +283,49 @@ private:
   uint32_t EventSection = 0;
 };
 
+class WasmSectionOrderChecker {
+public:
+  // We define orders for all core wasm sections and known custom sections.
+  enum : int {
+    // Core sections
+    // The order of standard sections is precisely given by the spec.
+    WASM_SEC_ORDER_TYPE = 1,
+    WASM_SEC_ORDER_IMPORT = 2,
+    WASM_SEC_ORDER_FUNCTION = 3,
+    WASM_SEC_ORDER_TABLE = 4,
+    WASM_SEC_ORDER_MEMORY = 5,
+    WASM_SEC_ORDER_GLOBAL = 6,
+    WASM_SEC_ORDER_EVENT = 7,
+    WASM_SEC_ORDER_EXPORT = 8,
+    WASM_SEC_ORDER_START = 9,
+    WASM_SEC_ORDER_ELEM = 10,
+    WASM_SEC_ORDER_DATACOUNT = 11,
+    WASM_SEC_ORDER_CODE = 12,
+    WASM_SEC_ORDER_DATA = 13,
+
+    // Custom sections
+    // "dylink" should be the very first section in the module
+    WASM_SEC_ORDER_DYLINK = 0,
+    // "linking" section requires DATA section in order to validate data symbols
+    WASM_SEC_ORDER_LINKING = 100,
+    // Must come after "linking" section in order to validate reloc indexes.
+    WASM_SEC_ORDER_RELOC = 101,
+    // "name" section must appear after DATA. Comes after "linking" to allow
+    // symbol table to set default function name.
+    WASM_SEC_ORDER_NAME = 102,
+    // "producers" section must appear after "name" section.
+    WASM_SEC_ORDER_PRODUCERS = 103
+  };
+
+  bool isValidSectionOrder(unsigned ID, StringRef CustomSectionName = "");
+
+private:
+  int LastOrder = -1; // Lastly seen known section's order
+
+  // Returns -1 for unknown sections.
+  int getSectionOrder(unsigned ID, StringRef CustomSectionName = "");
+};
+
 } // end namespace object
 
 inline raw_ostream &operator<<(raw_ostream &OS, const object::WasmSymbol &Sym) {

Modified: llvm/trunk/lib/Object/WasmObjectFile.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Object/WasmObjectFile.cpp?rev=349221&r1=349220&r2=349221&view=diff
==============================================================================
--- llvm/trunk/lib/Object/WasmObjectFile.cpp (original)
+++ llvm/trunk/lib/Object/WasmObjectFile.cpp Fri Dec 14 16:58:12 2018
@@ -24,6 +24,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/LEB128.h"
+#include "llvm/Support/ScopedPrinter.h"
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
@@ -207,8 +208,8 @@ static wasm::WasmTable readTable(WasmObj
   return Table;
 }
 
-static Error readSection(WasmSection &Section,
-                         WasmObjectFile::ReadContext &Ctx) {
+static Error readSection(WasmSection &Section, WasmObjectFile::ReadContext &Ctx,
+                         WasmSectionOrderChecker &Checker) {
   Section.Offset = Ctx.Ptr - Ctx.Start;
   Section.Type = readUint8(Ctx);
   LLVM_DEBUG(dbgs() << "readSection type=" << Section.Type << "\n");
@@ -231,6 +232,13 @@ static Error readSection(WasmSection &Se
     Ctx.Ptr += SectionNameSize;
     Size -= SectionNameSize;
   }
+
+  if (!Checker.isValidSectionOrder(Section.Type, Section.Name)) {
+    return make_error<StringError>("Out of order section type: " +
+                                       llvm::to_string(Section.Type),
+                                   object_error::parse_failed);
+  }
+
   Section.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
   Ctx.Ptr += Size;
   return Error::success();
@@ -265,8 +273,9 @@ WasmObjectFile::WasmObjectFile(MemoryBuf
   }
 
   WasmSection Sec;
+  WasmSectionOrderChecker Checker;
   while (Ctx.Ptr < Ctx.End) {
-    if ((Err = readSection(Sec, Ctx)))
+    if ((Err = readSection(Sec, Ctx, Checker)))
       return;
     if ((Err = parseSection(Sec)))
       return;
@@ -1433,3 +1442,58 @@ WasmObjectFile::getWasmRelocation(DataRe
   assert(Ref.d.b < Sec.Relocations.size());
   return Sec.Relocations[Ref.d.b];
 }
+
+int WasmSectionOrderChecker::getSectionOrder(unsigned ID,
+                                             StringRef CustomSectionName) {
+  switch (ID) {
+  case wasm::WASM_SEC_CUSTOM:
+    return StringSwitch<unsigned>(CustomSectionName)
+        .Case("dylink", WASM_SEC_ORDER_DYLINK)
+        .Case("linking", WASM_SEC_ORDER_LINKING)
+        .StartsWith("reloc.", WASM_SEC_ORDER_RELOC)
+        .Case("name", WASM_SEC_ORDER_NAME)
+        .Case("producers", WASM_SEC_ORDER_PRODUCERS)
+        .Default(-1);
+  case wasm::WASM_SEC_TYPE:
+    return WASM_SEC_ORDER_TYPE;
+  case wasm::WASM_SEC_IMPORT:
+    return WASM_SEC_ORDER_IMPORT;
+  case wasm::WASM_SEC_FUNCTION:
+    return WASM_SEC_ORDER_FUNCTION;
+  case wasm::WASM_SEC_TABLE:
+    return WASM_SEC_ORDER_TABLE;
+  case wasm::WASM_SEC_MEMORY:
+    return WASM_SEC_ORDER_MEMORY;
+  case wasm::WASM_SEC_GLOBAL:
+    return WASM_SEC_ORDER_GLOBAL;
+  case wasm::WASM_SEC_EXPORT:
+    return WASM_SEC_ORDER_EXPORT;
+  case wasm::WASM_SEC_START:
+    return WASM_SEC_ORDER_START;
+  case wasm::WASM_SEC_ELEM:
+    return WASM_SEC_ORDER_ELEM;
+  case wasm::WASM_SEC_CODE:
+    return WASM_SEC_ORDER_CODE;
+  case wasm::WASM_SEC_DATA:
+    return WASM_SEC_ORDER_DATA;
+  case wasm::WASM_SEC_DATACOUNT:
+    return WASM_SEC_ORDER_DATACOUNT;
+  case wasm::WASM_SEC_EVENT:
+    return WASM_SEC_ORDER_EVENT;
+  default:
+    llvm_unreachable("invalid section");
+  }
+}
+
+bool WasmSectionOrderChecker::isValidSectionOrder(unsigned ID,
+                                                  StringRef CustomSectionName) {
+  int Order = getSectionOrder(ID, CustomSectionName);
+  if (Order == -1) // Skip unknown sections
+    return true;
+  // There can be multiple "reloc." sections. Otherwise there shouldn't be any
+  // duplicate section orders.
+  bool IsValid = (LastOrder == Order && Order == WASM_SEC_ORDER_RELOC) ||
+                 LastOrder < Order;
+  LastOrder = Order;
+  return IsValid;
+}

Added: llvm/trunk/test/Object/Inputs/WASM/invalid-section-order.wasm
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Object/Inputs/WASM/invalid-section-order.wasm?rev=349221&view=auto
==============================================================================
Binary files llvm/trunk/test/Object/Inputs/WASM/invalid-section-order.wasm (added) and llvm/trunk/test/Object/Inputs/WASM/invalid-section-order.wasm Fri Dec 14 16:58:12 2018 differ

Added: llvm/trunk/test/Object/wasm-invalid-section-order.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Object/wasm-invalid-section-order.test?rev=349221&view=auto
==============================================================================
--- llvm/trunk/test/Object/wasm-invalid-section-order.test (added)
+++ llvm/trunk/test/Object/wasm-invalid-section-order.test Fri Dec 14 16:58:12 2018
@@ -0,0 +1,16 @@
+# RUN: not obj2yaml %p/Inputs/WASM/invalid-section-order.wasm 2>&1 | FileCheck %s
+# CHECK: {{.*}}: Out of order section type: 10
+
+# Inputs/WASM/invalid-section-order.wasm is generated from this ll file, by
+# modifying WasmObjectWriter to incorrectly write the data section before the
+# code section.
+#
+# target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+# target triple = "wasm32-unknown-unknown"
+#
+# @data = global i32 0, align 4
+#
+# define void @foo() {
+# entry:
+#   ret void
+# }

Added: llvm/trunk/test/ObjectYAML/wasm/invalid_section_order.yaml
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/ObjectYAML/wasm/invalid_section_order.yaml?rev=349221&view=auto
==============================================================================
--- llvm/trunk/test/ObjectYAML/wasm/invalid_section_order.yaml (added)
+++ llvm/trunk/test/ObjectYAML/wasm/invalid_section_order.yaml Fri Dec 14 16:58:12 2018
@@ -0,0 +1,20 @@
+# RUN: not yaml2obj %s -o /dev/null 2>&1 | FileCheck %s
+
+--- !WASM
+FileHeader:
+  Version:         0x00000001
+Sections:
+  - Type:            TYPE
+    Signatures:
+      - Index:           0
+        ReturnType:      NORESULT
+        ParamTypes:      []
+  - Type:            CODE
+    Functions:
+      - Index:           0
+        Locals:          []
+        Body:            0B
+  # CHECK: Out of order section type: 3
+  - Type:            FUNCTION
+    FunctionTypes:   [ 0 ]
+...

Modified: llvm/trunk/tools/yaml2obj/yaml2wasm.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/yaml2obj/yaml2wasm.cpp?rev=349221&r1=349220&r2=349221&view=diff
==============================================================================
--- llvm/trunk/tools/yaml2obj/yaml2wasm.cpp (original)
+++ llvm/trunk/tools/yaml2obj/yaml2wasm.cpp Fri Dec 14 16:58:12 2018
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 //
 
+#include "llvm/Object/Wasm.h"
 #include "llvm/ObjectYAML/ObjectYAML.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/LEB128.h"
@@ -516,7 +517,15 @@ int WasmWriter::writeWasm(raw_ostream &O
   writeUint32(OS, Obj.Header.Version);
 
   // Write each section
+  llvm::object::WasmSectionOrderChecker Checker;
   for (const std::unique_ptr<WasmYAML::Section> &Sec : Obj.Sections) {
+    StringRef SecName = "";
+    if (auto S = dyn_cast<WasmYAML::CustomSection>(Sec.get()))
+      SecName = S->Name;
+    if (!Checker.isValidSectionOrder(Sec->Type, SecName)) {
+      errs() << "Out of order section type: " << Sec->Type << "\n";
+      return 1;
+    }
     encodeULEB128(Sec->Type, OS);
     std::string OutString;
     raw_string_ostream StringStream(OutString);




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