Sampling next seed by weight (hit_count, bitmap_size, exec_us)
MODIFY
include/afl-fuzz.h
include/afl-fuzz.h
@@ -168,7 +168,8 @@ struct queue_entry {
u8 *trace_mini; /* Trace bytes, if kept */
u32 tc_ref; /* Trace bytes ref count */
- double perf_score; /* performance score */
+ double perf_score, /* performance score */
+ weight;
u8 *testcase_buf; /* The testcase buffer, if loaded. */

MODIFY
src/afl-fuzz-one.c
src/afl-fuzz-one.c
@@ -445,8 +445,10 @@ u8 fuzz_one_original(afl_state_t *afl) {
if (unlikely(afl->not_on_tty)) {
- ACTF("Fuzzing test case #%u (%u total, %llu uniq crashes found)...",
- afl->current_entry, afl->queued_paths, afl->unique_crashes);
+ ACTF("Fuzzing test case #%u (%u total, %llu uniq crashes found, perf_score=%0.0f, exec_us=%llu, hits=%u, map=%u)...",
+ afl->current_entry, afl->queued_paths, afl->unique_crashes,
+ afl->queue_cur->perf_score, afl->queue_cur->exec_us,
+ afl->n_fuzz[afl->queue_cur->n_fuzz_entry], afl->queue_cur->bitmap_size);
fflush(stdout);
}

MODIFY
src/afl-fuzz-queue.c
src/afl-fuzz-queue.c
@@ -42,6 +42,21 @@ inline u32 select_next_queue_entry(afl_state_t *afl) {
}
+double compute_weight(afl_state_t *afl, struct queue_entry *q, double avg_exec_us, double avg_bitmap_size) {
+
+ u32 hits = afl->n_fuzz[q->n_fuzz_entry];
+ if (hits == 0) hits = 1;
+
+ double weight = 1.0;
+ weight *= avg_exec_us / q->exec_us;
+ weight *= log(q->bitmap_size) / avg_bitmap_size;
+ weight /= log10(hits) + 1;
+
+ if (q->favored) weight *= 5;
+
+ return weight;
+}
+
/* create the alias table that allows weighted random selection - expensive */
void create_alias_table(afl_state_t *afl) {
@@ -65,25 +80,35 @@ void create_alias_table(afl_state_t *afl) {
memset((void *)afl->alias_table, 0, n * sizeof(u32));
memset((void *)afl->alias_probability, 0, n * sizeof(double));
- double sum = 0;
-
+ double avg_exec_us = 0.0;
+ double avg_bitmap_size = 0.0;
for (i = 0; i < n; i++) {
struct queue_entry *q = afl->queue_buf[i];
-
- if (!q->disabled) { q->perf_score = calculate_score(afl, q); }
-
- sum += q->perf_score;
+ avg_exec_us += q->exec_us;
+ avg_bitmap_size += log(q->bitmap_size);
}
+ avg_exec_us /= afl->queued_paths;
+ avg_bitmap_size /= afl->queued_paths;
+ double sum = 0;
for (i = 0; i < n; i++) {
struct queue_entry *q = afl->queue_buf[i];
- P[i] = (q->perf_score * n) / sum;
+ if (!q->disabled) {
+ q->weight = compute_weight(afl, q, avg_exec_us, avg_bitmap_size);
+ q->perf_score = calculate_score(afl, q);
}
+ sum += q->weight;
+
+ }
+
+ for (i = 0; i < n; i++)
+ P[i] = (afl->queue_buf[i]->weight * n) / sum;
+
int nS = 0, nL = 0, s;
for (s = (s32)n - 1; s >= 0; --s) {

Sampling next seed by weight (hit_count, bitmap_size, exec_us)