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George Dunlap
2b1cde7783
Finding aggregate coverage for a set of test files means running each afl-generated test case through the harness. At the moment, this is done by re-executing afl-harness-cov with each input file. When a large number of test cases have been generated, this can take a significant amonut of time; a recent test with 30k total files generated by 4 parallel fuzzers took over 7 minutes. The vast majority of this time is taken up with 'exec', however. Since the harness is already designed to loop over multiple inputs for llvm "persistent mode", just allow it to take a large number of inputs on the same when *not* running in llvm "persistent mode".. Then the command can be efficiently executed like this: ls */queue/id* | xargs $path/afl-harness-cov For the above-mentioned test on 30k files, the time to generate coverage data was reduced from 7 minutes to under 30 seconds. Signed-off-by: George Dunlap <george.dunlap@citrix.com> Acked-by: Jan Beulich <jbeulich@suse.com> Acked-by: Andrew Cooper <andrew.cooper3@citrix.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.