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author | Peter Maydell <peter.maydell@linaro.org> | 2020-10-26 13:16:29 +0000 |
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committer | Peter Maydell <peter.maydell@linaro.org> | 2020-10-26 13:16:29 +0000 |
commit | e75de8354ac5c67145b2f8874d3c36022d4a94bb (patch) | |
tree | 206d434e58d9d0b40c98c4507582c4d1adc32127 /docs/devel | |
parent | 288a1cc6345ed0b04e0dc887905ebeef17141608 (diff) | |
parent | 28bbe20ce281659e317b807f34f568bde6d99760 (diff) | |
download | qemu-e75de8354ac5c67145b2f8874d3c36022d4a94bb.zip qemu-e75de8354ac5c67145b2f8874d3c36022d4a94bb.tar.gz qemu-e75de8354ac5c67145b2f8874d3c36022d4a94bb.tar.bz2 |
Merge remote-tracking branch 'remotes/huth-gitlab/tags/pull-request-2020-10-26' into staging
* qtest fixes (e.g. memory leaks)
* Fix for Xen dummy cpu loop (which happened due to qtest accel rework)
* Introduction of the generic device fuzzer
* Run more check-acceptance tests in the gitlab-CI
# gpg: Signature made Mon 26 Oct 2020 09:34:04 GMT
# gpg: using RSA key 27B88847EEE0250118F3EAB92ED9D774FE702DB5
# gpg: issuer "thuth@redhat.com"
# gpg: Good signature from "Thomas Huth <th.huth@gmx.de>" [full]
# gpg: aka "Thomas Huth <thuth@redhat.com>" [full]
# gpg: aka "Thomas Huth <huth@tuxfamily.org>" [full]
# gpg: aka "Thomas Huth <th.huth@posteo.de>" [unknown]
# Primary key fingerprint: 27B8 8847 EEE0 2501 18F3 EAB9 2ED9 D774 FE70 2DB5
* remotes/huth-gitlab/tags/pull-request-2020-10-26: (31 commits)
tests/acceptance: Use .ppm extention for Portable PixMap files
tests/acceptance: Remove unused import
test/docker/dockerfiles: Add missing packages for acceptance tests
tests/acceptance: Enable AVOCADO_ALLOW_UNTRUSTED_CODE in the gitlab-CI
test/acceptance: Remove the CONTINUOUS_INTEGRATION tags
tests/acceptance/ppc_prep_40p: Fix the URL to the NetBSD-4.0 archive
scripts/oss-fuzz: ignore the generic-fuzz target
scripts/oss-fuzz: use hardlinks instead of copying
fuzz: register predefined generic-fuzz configs
fuzz: add generic-fuzz configs for oss-fuzz
fuzz: add an "opaque" to the FuzzTarget struct
fuzz: Add instructions for using generic-fuzz
scripts/oss-fuzz: Add crash trace minimization script
scripts/oss-fuzz: Add script to reorder a generic-fuzzer trace
fuzz: add a crossover function to generic-fuzzer
fuzz: add a DISABLE_PCI op to generic-fuzzer
fuzz: Add support for custom crossover functions
fuzz: Add fuzzer callbacks to DMA-read functions
fuzz: Declare DMA Read callback function
fuzz: Add DMA support to the generic-fuzzer
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'docs/devel')
-rw-r--r-- | docs/devel/fuzzing.txt | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/docs/devel/fuzzing.txt b/docs/devel/fuzzing.txt index 96d71c9..03585c1 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 == |