We have a few cases or reported issues which are about a timeout to parse
the input in 25 s. In all cases, the input is a few hundred kb. We don't really
care if the config parsers are super efficent, so let's set a limit on the input
size to avoid triggering such issues. The parsers often contain quadratic
algorithms. This is OK, because the numbers of elements are almost always very
small in real use. Rewriting the code to use more complicated data structures
to speed this up would not only complicate the code, but also pessimize behaviour
for the overwhelmingly common case of small samples. Note that in all those
cases, the input data is trusted. We care about memory correctness, and not
not so much about efficiency.
The size checks are done twice: using options for libfuzzer, and using an
internal check for afl. Those should be changed together. I didn't use a define,
because there is no easy mechanism to share the define between the two files.
Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11587.
We had a sample which was large enough that write(2) failed to push all the
data into the pipe, and an assert failed. The code could be changed to use
a loop, but then we'd need to interleave writes and sd_event_run (to process
the journal). I don't think the complexity is worth it — fuzzing works best
if the sample is not too huge anyway. So let's just reject samples above 64k,
and tell oss-fuzz about this limit.
This splits out a bunch of functions from fileio.c that have to do with
temporary files. Simply to make the header files a bit shorter, and to
group things more nicely.
No code changes, just some rearranging of source files.
This should help to catch issues that are easily detectable by
bad_build_check like the one being fixed in https://github.com/systemd/systemd/pull/10793,
which would totally break the build tomorrow if I hadn't run
`helper.py check_build` manually.
This is a follow-up to 8857fb9beb that prevents the fuzzer from crashing with
```
==220==ERROR: AddressSanitizer: ABRT on unknown address 0x0000000000dc (pc 0x7ff4953c8428 bp 0x7ffcf66ec290 sp 0x7ffcf66ec128 T0)
SCARINESS: 10 (signal)
#0 0x7ff4953c8427 in gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x35427)
#1 0x7ff4953ca029 in abort (/lib/x86_64-linux-gnu/libc.so.6+0x37029)
#2 0x7ff49666503a in log_assert_failed_realm /work/build/../../src/systemd/src/basic/log.c:805:9
#3 0x7ff496614ecf in safe_close /work/build/../../src/systemd/src/basic/fd-util.c:66:17
#4 0x548806 in server_done /work/build/../../src/systemd/src/journal/journald-server.c:2064:9
#5 0x5349fa in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/fuzz/fuzz-journald-kmsg.c:26:9
#6 0x592755 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/libfuzzer/FuzzerLoop.cpp:571:15
#7 0x590627 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*) /src/libfuzzer/FuzzerLoop.cpp:480:3
#8 0x594432 in fuzzer::Fuzzer::MutateAndTestOne() /src/libfuzzer/FuzzerLoop.cpp:708:19
#9 0x5973c6 in fuzzer::Fuzzer::Loop(std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, fuzzer::fuzzer_allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&) /src/libfuzzer/FuzzerLoop.cpp:839:5
#10 0x574541 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/libfuzzer/FuzzerDriver.cpp:764:6
#11 0x5675fc in main /src/libfuzzer/FuzzerMain.cpp:20:10
#12 0x7ff4953b382f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
#13 0x420f58 in _start (/out/fuzz-journald-kmsg+0x420f58)
```
I went through my antique collection of fuzzers the other day
to see which ones I hadn't sent upstream yet. This one
seems to be nice to have and ready to be merged. As far as I can
tell, it hasn't managed to find anything useful yet,
but it's better to be safe than sorry especially when it comes to networking
code :-)
