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Fix fuzzer generation of a DataSegment + add validation that would have caught it #6626

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merged 8 commits into from
May 23, 2024
Merged

Fix fuzzer generation of a DataSegment + add validation that would have caught it #6626

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20ce9d3
start
kripken May 23, 2024
1d6dde2
work
kripken May 23, 2024
195d558
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kripken May 23, 2024
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kripken May 23, 2024
fc3061a
fix
kripken May 23, 2024
c4f3913
fix name collision
kripken May 23, 2024
617412e
Update src/wasm/wasm-validator.cpp
kripken May 23, 2024
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kripken May 23, 2024
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7 changes: 4 additions & 3 deletions src/tools/fuzzing/fuzzing.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -224,13 +224,14 @@ void TranslateToFuzzReader::setupMemory() {
auto segment = builder.makeDataSegment();
segment->memory = memory->name;
segment->offset = builder.makeConst(int32_t(0));
segment->setName(Name::fromInt(0), false);
wasm.dataSegments.push_back(std::move(segment));
segment->setName(Names::getValidDataSegmentName(wasm, Name::fromInt(0)),
false);
auto num = upTo(USABLE_MEMORY * 2);
for (size_t i = 0; i < num; i++) {
auto value = upTo(512);
wasm.dataSegments[0]->data.push_back(value >= 256 ? 0 : (value & 0xff));
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Was this meant to be wasm.dataSegment[i]? It looks it should've been that way if the semantics are the same with the modified code..

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@kripken kripken May 23, 2024 •
edited
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Hmm, I think it is pushing num chunks of binary data to the first segment here. wasm.dataSegments[i] might not exist - all we know is that [0] exists.

What do you mean by the second sentence?

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Sorry I was confused.. Nevermind.

segment->data.push_back(value >= 256 ? 0 : (value & 0xff));
}
wasm.addDataSegment(std::move(segment));
}
}

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58 changes: 56 additions & 2 deletions src/wasm/wasm-validator.cpp
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Expand Up @@ -3908,7 +3908,7 @@ static void validateTags(Module& module, ValidationInfo& info) {
}
}

static void validateModule(Module& module, ValidationInfo& info) {
static void validateStart(Module& module, ValidationInfo& info) {
// start
if (module.start.is()) {
auto func = module.getFunctionOrNull(module.start);
Expand All @@ -3924,6 +3924,59 @@ static void validateModule(Module& module, ValidationInfo& info) {
}
}

namespace {
template<typename T, typename U>
void validateModuleMap(Module& module,
ValidationInfo& info,
T& list,
U getter,
const std::string& kind) {
// Given a list of module elements (like exports or globals), see that we can
// get the items using the getter (getExportorNull, etc.). The getter uses the
// lookup map internally, so this validates that they contain all items in
// the list.
for (auto& item : list) {
auto* ptr = (module.*getter)(item->name);
if (!ptr) {
info.fail(kind + " must be found (use updateMaps)", item->name, nullptr);
} else {
info.shouldBeEqual(item->name,
ptr->name,
item->name,
"getter must return the correct item");
}
}

// TODO: Also check there is nothing extraneous in the map, but that would
// require inspecting private fields of Module.
}
} // anonymous namespace

static void validateModuleMaps(Module& module, ValidationInfo& info) {
// Module maps should be up to date.
validateModuleMap(
module, info, module.exports, &Module::getExportOrNull, "Export");
validateModuleMap(
module, info, module.functions, &Module::getFunctionOrNull, "Function");
validateModuleMap(
module, info, module.globals, &Module::getGlobalOrNull, "Global");
validateModuleMap(module, info, module.tags, &Module::getTagOrNull, "Tag");
validateModuleMap(module,
info,
module.elementSegments,
&Module::getElementSegmentOrNull,
"ElementSegment");
validateModuleMap(
module, info, module.memories, &Module::getMemoryOrNull, "Memory");
validateModuleMap(module,
info,
module.dataSegments,
&Module::getDataSegmentOrNull,
"DataSegment");
validateModuleMap(
module, info, module.tables, &Module::getTableOrNull, "Table");
}

static void validateFeatures(Module& module, ValidationInfo& info) {
if (module.features.hasGC()) {
info.shouldBeTrue(module.features.hasReferenceTypes(),
Expand Down Expand Up @@ -4004,7 +4057,8 @@ bool WasmValidator::validate(Module& module, Flags flags) {
validateDataSegments(module, info);
validateTables(module, info);
validateTags(module, info);
validateModule(module, info);
validateStart(module, info);
validateModuleMaps(module, info);
validateFeatures(module, info);
if (info.closedWorld) {
validateClosedWorldInterface(module, info);
Expand Down
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