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Andrew Cooper
b163e550df
AFL has a measure of stability, where it passes the same corpus into the
fuzzing harness and observes whether the execution path changes from before.
Any instability in the fuzzing harness reduces its effectiveness, as an
observed crash may not reliably be caused by the original corpus.
In preparation to fix a stability bug, introduce struct fuzz_state, allocated
on the stack and passed around via struct x86_emulate_ctxt's data parameter.
Propagate ctxt into the helpers such as maybe_fail(), so the state can be
retrieved.
Move the previously-static data_{index,num} into struct fuzz_state.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
# OVERVIEW This directory provides fuzzing targets to be run inside Google oss-fuzz infrastructure. See also https://github.com/google/oss-fuzz. # HOW IT WORKS We need to provide the source code and the rune to produce objects or archives (artefacts) from source code. These items ideally should live inside xen.git so that they can be kept up to date. The artefacts contain all the code we wish to fuzz and a function called LLVMFuzzerTestOneInput. LLVMFuzzerTestOneInput is the entry point to the code we wish to fuzz. Note that we don't produce executable programs because we don't have libFuzzEngine locally. libFuzzEngine is maintained by oss-fuzz. We also provide build script to oss-fuzz. The build script will inherit the correct compiler settings and be run in a pre-setup environment, which has libFuzzEngine installed. The build script is responsible for calling the correct Xen build rune to produce the artefacts, then link them against libFuzzEngine to produce executables, which will run in oss-fuzz infrastructure. Please refer to official oss-fuzz documents for the most up-to-date descriptions for all moving parts. # HOW TO IMPROVE THE FUZZING TARGETS Feel free to modify each fuzzing targets at will. Make sure they build by invoking make as you would build tools. To actually test the new code, you would need to run the target in standalone mode, please refer to oss-fuzz documents on how to do that. It is highly recommended that you run the new target for a while to weed out error in plumbing code to avoid false positives.