1# Overview 2 3This application is intended to fuzz test the SPDK vhost target by supplying 4malformed or invalid requests across a unix domain socket. This fuzzer 5currently supports fuzzing both vhost block and vhost scsi devices. When 6fuzzing a vhost scsi device, users can select whether to fuzz the scsi I/O 7queue or the scsi admin queue. Please see the NVMe fuzzer readme for information 8on how output is generated, debugging procedures, and the JSON format expected 9when supplying preconstructed values to the fuzzer. 10 11## Request Types 12 13Like the NVMe fuzzer, there is an example json file showing the types of requests 14that the application accepts. Since the vhost application accepts both vhost block 15and vhost scsi commands, there are three distinct object types that can be passed in 16to the application. 17 181. vhost_blk_cmd 192. vhost_scsi_cmd 203. vhost_scsi_mgmt_cmd 21 22Each one of these objects contains distinct data types and they should not be used interchangeably. 23 24All three of the data types begin with three iovec structures describing the request, data, and response 25memory locations. By default, these values are overwritten by the application even when supplied as part 26of a json file. This is because the request and resp data pointers are intended to point to portions of 27the data structure. 28 29If you want to override these iovec values using a json file, you can specify the -k option. 30In most cases, this will just result in the application failing all I/O immediately since 31the request will no longer point to a valid memory location. 32 33It is possible to supply all three types of requests in a single array to the application. They will be parsed and 34submitted to the proper block devices. 35 36## RPC 37 38The vhost fuzzer differs from the NVMe fuzzer in that it expects devices to be configured via rpc. The fuzzer should 39always be started with the --wait-for-rpc argument. Please see below for an example of starting the fuzzer. 40 41~~~bash 42./test/app/fuzz/vhost_fuzz/vhost_fuzz -t 30 --wait-for-rpc & 43./scripts/rpc.py fuzz_vhost_create_dev -s ./Vhost.1 -b -V 44./scripts/rpc.py fuzz_vhost_create_dev -s ./naa.VhostScsi0.1 -l -V 45./scripts/rpc.py framework_start_init 46~~~ 47