Skip to content

Fuzzer: Fix 64-bit max memory sizes, and add more variety #8899

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
kripken merged 2 commits into from
Jul 14, 2026
+10 −6
Merged

Fuzzer: Fix 64-bit max memory sizes, and add more variety #8899

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
a263a4f
fix
kripken Jul 10, 2026
cbf899a
fmt
kripken Jul 10, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
16 changes: 10 additions & 6 deletions src/tools/fuzzing/fuzzing.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -906,16 +906,20 @@ void TranslateToFuzzReader::finalizeMemory() {
}
memory->initial = std::max(memory->initial, fuzzParams->USABLE_MEMORY);
// Avoid an unlimited memory size, which would make fuzzing very difficult
// as different VMs will run out of system memory in different ways.
if (memory->max == Memory::kUnlimitedSize) {
// as different VMs will run out of system memory in different ways. Also use
// the initial memory size as the maximum, if the initial is now larger
// (which can happen as we compute the initial size, above: this is where we
// update the maximum to make sense relative to that new initial size).
if (memory->max == Memory::kUnlimitedSize || memory->max < memory->initial) {
memory->max = memory->initial;
}
if (memory->max <= memory->initial) {
if (memory->max == memory->initial && oneIn(2)) {
// To allow growth to work (which a testcase may assume), try to make the
// maximum larger than the initial.
// maximum larger than the initial, some of the time.
// TODO: scan the wasm for grow instructions?
memory->max =
std::min(Address(memory->initial + 1), Address(memory->maxSize32()));
memory->max = std::min(
Address(memory->initial + 1),
Address(memory->is64() ? memory->maxSize64() : memory->maxSize32()));
}

if (!preserveImportsAndExports) {
Expand Down
Loading