diff options
Diffstat (limited to 'docs/devel')
| -rw-r--r-- | docs/devel/fuzzing.txt | 39 | ||||
| -rw-r--r-- | docs/devel/testing.rst | 4 |
2 files changed, 41 insertions, 2 deletions
diff --git a/docs/devel/fuzzing.txt b/docs/devel/fuzzing.txt index 96d71c94d7..03585c1a9b 100644 --- a/docs/devel/fuzzing.txt +++ b/docs/devel/fuzzing.txt @@ -125,6 +125,45 @@ provided by libfuzzer. Libfuzzer passes a byte array and length. Commonly the fuzzer loops over the byte-array interpreting it as a list of qtest commands, addresses, or values. +== The Generic Fuzzer == +Writing a fuzz target can be a lot of effort (especially if a device driver has +not be built-out within libqos). Many devices can be fuzzed to some degree, +without any device-specific code, using the generic-fuzz target. + +The generic-fuzz target is capable of fuzzing devices over their PIO, MMIO, +and DMA input-spaces. To apply the generic-fuzz to a device, we need to define +two env-variables, at minimum: + +QEMU_FUZZ_ARGS= is the set of QEMU arguments used to configure a machine, with +the device attached. For example, if we want to fuzz the virtio-net device +attached to a pc-i440fx machine, we can specify: +QEMU_FUZZ_ARGS="-M pc -nodefaults -netdev user,id=user0 \ + -device virtio-net,netdev=user0" + +QEMU_FUZZ_OBJECTS= is a set of space-delimited strings used to identify the +MemoryRegions that will be fuzzed. These strings are compared against +MemoryRegion names and MemoryRegion owner names, to decide whether each +MemoryRegion should be fuzzed. These strings support globbing. For the +virtio-net example, we could use QEMU_FUZZ_OBJECTS= + * 'virtio-net' + * 'virtio*' + * 'virtio* pcspk' (Fuzz the virtio devices and the PC speaker...) + * '*' (Fuzz the whole machine) + +The "info mtree" and "info qom-tree" monitor commands can be especially useful +for identifying the MemoryRegion and Object names used for matching. + +As a generic rule-of-thumb, the more MemoryRegions/Devices we match, the greater +the input-space, and the smaller the probability of finding crashing inputs for +individual devices. As such, it is usually a good idea to limit the fuzzer to +only a few MemoryRegions. + +To ensure that these env variables have been configured correctly, we can use: + +./qemu-fuzz-i386 --fuzz-target=generic-fuzz -runs=0 + +The output should contain a complete list of matched MemoryRegions. + = Implementation Details = == The Fuzzer's Lifecycle == diff --git a/docs/devel/testing.rst b/docs/devel/testing.rst index 0c3e79d31c..0aa7a13bba 100644 --- a/docs/devel/testing.rst +++ b/docs/devel/testing.rst @@ -654,7 +654,7 @@ To manually install Avocado and its dependencies, run: Alternatively, follow the instructions on this link: - http://avocado-framework.readthedocs.io/en/latest/GetStartedGuide.html#installing-avocado + https://avocado-framework.readthedocs.io/en/latest/guides/user/chapters/installing.html Overview -------- @@ -837,7 +837,7 @@ Parameter reference To understand how Avocado parameters are accessed by tests, and how they can be passed to tests, please refer to:: - http://avocado-framework.readthedocs.io/en/latest/WritingTests.html#accessing-test-parameters + https://avocado-framework.readthedocs.io/en/latest/guides/writer/chapters/writing.html#accessing-test-parameters Parameter values can be easily seen in the log files, and will look like the following: |