With the guest memory size of 1MB, a valid descriptor size can be close
to the guest memory size (e.g. 1MB) and can contain close to 256k
valid pfn entries (each entry is 4 bytes). Multiplying the queue
size (e.g. 256), there can be close to 64 millions pfn entries to
process in a single request. This is why the oss-fuzz reported a
timeout (with a limit of 60s).
By reducing the guest memory size and the queue size, the worst-case now
is 8 million pfn entries for fuzzing, which can be finished in around 20
seconds according to my local experiment.
Signed-off-by: Bo Chen <chen.bo@intel.com>
As the virt queues are initialized with random bytes from the fuzzing
engine, a descriptor buffer for the available ring can have a very large
length (e.g. up to 4GB). This means there can be up to 1 billion
entries (e.g. page frame number) for virtio-balloon to process a signal
available descriptor (given each entry is 4 bytes). This is the reason
why oss-fuzz reported a hanging issue for this fuzzer, where the
generated descriptor buffer length is 4,278,321,152.
We can avoid this kind of long execution by reducing the size of guest
memory. For example, with 1MB of guest memory, the number of descriptor
entries for processing is limited ~256K.
Signed-off-by: Bo Chen <chen.bo@intel.com>
This function is for really for the transport layer to trigger a device
reset. Instead name it appropriately for the fuzzing specific use case.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The fuzzer exercises the inflate, deflate and reporting events of
virtio-balloon via creating three queues and kicking three events.
Signed-off-by: Bo Chen <chen.bo@intel.com>
