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Binary fuzz fix: disallow popping from outside a block #1305

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Merged
kripken merged 4 commits into from
Nov 28, 2017
Merged

Binary fuzz fix: disallow popping from outside a block #1305

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553f9f7
remove unneeded code to handle a br to the return from the function. …
kripken Nov 18, 2017
98a1251
test
kripken Nov 18, 2017
ce67500
fix a fuzz bug of popping from outside a block
kripken Nov 19, 2017
c5ddf45
Merge remote-tracking branch 'origin/master' into pop-outside-block
kripken Nov 22, 2017
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6 changes: 6 additions & 0 deletions src/wasm/wasm-binary.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2175,6 +2175,9 @@ BinaryConsts::ASTNodes WasmBinaryBuilder::readExpression(Expression*& curr) {
}

void WasmBinaryBuilder::pushBlockElements(Block* curr, size_t start, size_t end) {
assert(start <= expressionStack.size());
assert(start <= end);
assert(end <= expressionStack.size());
// the first dropped element may be consumed by code later - it was on the stack first,
// and is the only thing left on the stack. there must be just one thing on the stack
// since we are at the end of a block context. note that we may need to drop more than
Expand Down Expand Up @@ -2255,6 +2258,9 @@ Expression* WasmBinaryBuilder::getBlockOrSingleton(WasmType type) {
auto start = expressionStack.size();
processExpressions();
size_t end = expressionStack.size();
if (end < start) {
throw ParseException("block cannot pop from outside");
}
breakStack.pop_back();
auto* block = allocator.alloc<Block>();
pushBlockElements(block, start, end);
Expand Down