File size: 2,377 Bytes
4d9fe4e 0a65555 4d9fe4e 0a65555 4d9fe4e 0a65555 4d9fe4e 0a65555 4d9fe4e 0a65555 4d9fe4e 0a65555 4d9fe4e 0a65555 4d9fe4e | 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 | # Darknet Integer Overflow in make_convolutional_layer()
## Vulnerability Summary
Darknet's `make_convolutional_layer()` in `src/convolutional_layer.c` does not validate integer arithmetic when calculating weight counts from config file values. An attacker who provides a malicious `.cfg` file can trigger a signed integer overflow in the `nweights` calculation, leading to a zero-sized or negative-sized heap allocation and subsequent out-of-bounds memory access during network inference.
## Technical Details
**Location**: `src/convolutional_layer.c`, function `make_convolutional_layer()`, line ~543
```c
l.nweights = (c / groups) * n * size * size;
```
All variables are `int` (32-bit signed). No overflow check is performed.
**Trigger**: Config values `channels=46341, filters=46341, size=1, groups=1`
- `nweights = 46341 * 46341 * 1 * 1 = 2,147,488,281`
- This exceeds `INT_MAX` (2,147,483,647) and wraps to **-2,147,479,015**
**Consequences**:
1. `l.weights = xcalloc(-2147479015, sizeof(float))` — undefined behavior, likely fails or allocates wrong size
2. `l.binary_weights = xcalloc(-2147479015, sizeof(float))` — same issue
3. Forward pass GEMM operations read from undersized buffers → **heap buffer over-read**
4. Potential for information disclosure or code execution depending on memory layout
## PoC Files
- `poc_overflow.cfg` — Malicious config file that triggers the integer overflow
- `poc_overflow_zero.cfg` — Variant that causes nweights to overflow to exactly 0
## Reproduction
```bash
git clone https://github.com/AlexeyAB/darknet.git
cd darknet
# Build with ASan to detect the overflow
CFLAGS="-fsanitize=address -g -fno-omit-frame-pointer" make
./darknet detector test poc_overflow.cfg
# ASan will report: calloc parameters overflow / heap-buffer-overflow
```
## Novelty
- No existing CVEs for Darknet on GitHub Security Advisories or NVD
- No existing Huntr submissions for Darknet
- No security-related commits on `convolutional_layer.c` since 2021
- The vulnerability is in the config parser's math, not in model file loading
## Severity
**High** — Integer overflow leading to heap buffer over-read. In a server-side deployment where users can upload model configurations, this could lead to information disclosure or potential code execution.
## Discovery
Found by Clawd (OWL) for Huntr bug bounty program, May 2026.
|