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e38ddc90
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2018-07-26T15:41:41
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fuzzers: limit maximum pack object count
By default, libgit2 allows up to 2^32 objects when downloading a
packfile from a remote. For each of these objects, libgit2 will allocate
up to two small structs, which in total adds up to quite a lot of
memory. As a result, our fuzzers might run out of memory rather quick in
case where they receive as input a packfile with such a huge count of
objects.
Limit the packfile object count to 10M objects. This is sufficiently big
to still work with most largish repos (linux.git has around 6M objects
as of now), but small enough to not cause the fuzzer to OOM.
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59328ed8
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2018-07-19T13:29:46
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fuzzers: rename "fuzz" directory to match our style
Our layout uses names like "examples" or "tests" which is why the "fuzz"
directory doesn't really fit in here. Rename the directory to be called
"fuzzers" instead. Furthermore, we rename the fuzzer "fuzz_packfile_raw"
to "packfile_raw_fuzzer", which is also in line with the already
existing fuzzer at google/oss-fuzz.
While at it, rename the "packfile_raw" fuzzer to instead just be called
"packfile" fuzzer.
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de53972f
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2018-07-20T11:07:47
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fuzzers: avoid use of libgit2 internals in packfile_raw
The packfile_raw fuzzer is using some internal APIs from libgit2, which
makes it hard to compile it as part of the oss-fuzz project. As oss-fuzz
requires us to link against the C++ FuzzingEngine library, we cannot use
"-DBUILD_FUZZERS=ON" directly but instead have to first compile an
object from our fuzzers and then link against the C++ library. Compiling
the fuzzer objects thus requires an external invocation of CC, and we
certainly don't want to do further black magic by adding libgit2's
private source directory to the header include path.
To fix the issue, convert the code to not use any internal APIs. Besides
some headers which we have to add now, this also requires us to change
to the hashing function of the ODB. Note that this will change the
hashing result, as we have previously not prepended the object header to
the data that is to be hashed. But this shouldn't matter in practice, as
we don't care for the hash value anyway.
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