@@ -804,6 +804,92 @@ static void general_pre_fuzz(QTestState *s)
counter_shm_init();
}
+
+/*
+ * When libfuzzer gives us two inputs to combine, return a new input with the
+ * following structure:
+ *
+ * Input 1 (data1)
+ * SEPARATOR
+ * Clear out the DMA Patterns
+ * SEPARATOR
+ * Disable the pci_read/write instructions
+ * SEPARATOR
+ * Input 2 (data2)
+ *
+ * The idea is to collate the core behaviors of the two inputs.
+ * For example:
+ * Input 1: maps a device's BARs, sets up three DMA patterns, and triggers
+ * device functionality A
+ * Input 2: maps a device's BARs, sets up one DMA pattern, and triggers device
+ * functionality B
+ *
+ * This function attempts to produce an input that:
+ * Ouptut: maps a device's BARs, set up three DMA patterns, triggers
+ * functionality A device, replaces the DMA patterns with a single
+ * patten, and triggers device functionality B.
+ */
+static size_t general_fuzz_crossover(const uint8_t *data1, size_t size1, const
+ uint8_t *data2, size_t size2, uint8_t *out,
+ size_t max_out_size, unsigned int seed)
+{
+ size_t copy_len = 0, size = 0;
+
+ /* Check that we have enough space for data1 and at least part of data2 */
+ if (max_out_size <= size1 + strlen(SEPARATOR) * 3 + 2) {
+ return 0;
+ }
+
+ /* Copy_Len in the first input */
+ copy_len = size1;
+ memcpy(out + size, data1, copy_len);
+ size += copy_len;
+ max_out_size -= copy_len;
+
+ /* Append a separator */
+ copy_len = strlen(SEPARATOR);
+ memcpy(out + size, SEPARATOR, copy_len);
+ size += copy_len;
+ max_out_size -= copy_len;
+
+ /* Clear out the DMA Patterns */
+ copy_len = 1;
+ if (copy_len) {
+ out[size] = OP_CLEAR_DMA_PATTERNS;
+ }
+ size += copy_len;
+ max_out_size -= copy_len;
+
+ /* Append a separator */
+ copy_len = strlen(SEPARATOR);
+ memcpy(out + size, SEPARATOR, copy_len);
+ size += copy_len;
+ max_out_size -= copy_len;
+
+ /* Disable PCI ops. Assume data1 took care of setting up PCI */
+ copy_len = 1;
+ if (copy_len) {
+ out[size] = OP_DISABLE_PCI;
+ }
+ size += copy_len;
+ max_out_size -= copy_len;
+
+ /* Append a separator */
+ copy_len = strlen(SEPARATOR);
+ memcpy(out + size, SEPARATOR, copy_len);
+ size += copy_len;
+ max_out_size -= copy_len;
+
+ /* Copy_Len over the second input */
+ copy_len = MIN(size2, max_out_size);
+ memcpy(out + size, data2, copy_len);
+ size += copy_len;
+ max_out_size -= copy_len;
+
+ return size;
+}
+
+
static GString *general_fuzz_cmdline(FuzzTarget *t)
{
GString *cmd_line = g_string_new(TARGET_NAME);
@@ -823,7 +909,9 @@ static void register_general_fuzz_targets(void)
.description = "Fuzz based on any qemu command-line args. ",
.get_init_cmdline = general_fuzz_cmdline,
.pre_fuzz = general_pre_fuzz,
- .fuzz = general_fuzz});
+ .fuzz = general_fuzz,
+ .crossover = general_fuzz_crossover
+ });
}
fuzz_target_init(register_general_fuzz_targets);