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fuzz: add a crossover function to generic-fuzzer

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Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20201023150746.107063-10-alxndr@bu.edu>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This commit is contained in:
Alexander Bulekov 2020-10-23 11:07:38 -04:00 committed by Thomas Huth
parent ccbd4bc8af
commit a253932227
1 changed files with 86 additions and 0 deletions
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86
tests/qtest/fuzz/generic_fuzz.c
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@ -810,6 +810,91 @@ static void generic_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 generic_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 *generic_fuzz_cmdline(FuzzTarget *t)
{
GString *cmd_line = g_string_new(TARGET_NAME);
@ -830,6 +915,7 @@ static void register_generic_fuzz_targets(void)
.get_init_cmdline = generic_fuzz_cmdline,
.pre_fuzz = generic_pre_fuzz,
.fuzz = generic_fuzz,
.crossover = generic_fuzz_crossover
});
}