From bb472fd42ea14320c37515418f38ad33eee0b639 Mon Sep 17 00:00:00 2001 From: Evgeny Vereshchagin Date: Sun, 20 May 2018 15:07:07 +0200 Subject: [PATCH] basic/random-util: do not use getrandom() under msan `fuzz-journal-remote` seems to be failing under `msan` as soon as it starts: $ sudo infra/helper.py run_fuzzer systemd fuzz-journal-remote Running: docker run --rm -i --privileged -e FUZZING_ENGINE=libfuzzer -v /home/vagrant/oss-fuzz/build/out/systemd:/out -t gcr.io/oss-fuzz-base/base-runner run_fuzzer fuzz-journal-remote Using seed corpus: fuzz-journal-remote_seed_corpus.zip /out/fuzz-journal-remote -rss_limit_mb=2048 -timeout=25 /tmp/fuzz-journal-remote_corpus -max_len=65536 < /dev/null INFO: Seed: 3380449479 INFO: Loaded 2 modules (36336 inline 8-bit counters): 36139 [0x7ff36ea31d39, 0x7ff36ea3aa64), 197 [0x9998c8, 0x99998d), INFO: Loaded 2 PC tables (36336 PCs): 36139 [0x7ff36ea3aa68,0x7ff36eac7d18), 197 [0x999990,0x99a5e0), INFO: 2 files found in /tmp/fuzz-journal-remote_corpus INFO: seed corpus: files: 2 min: 4657b max: 7790b total: 12447b rss: 97Mb Uninitialized bytes in __interceptor_pwrite64 at offset 24 inside [0x7fffdd4d7230, 240) ==15==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x7ff36e685e8a in journal_file_init_header /work/build/../../src/systemd/src/journal/journal-file.c:436:13 #1 0x7ff36e683a9d in journal_file_open /work/build/../../src/systemd/src/journal/journal-file.c:3333:21 #2 0x7ff36e68b8f6 in journal_file_open_reliably /work/build/../../src/systemd/src/journal/journal-file.c:3520:13 #3 0x4a3f35 in open_output /work/build/../../src/systemd/src/journal-remote/journal-remote.c:70:13 #4 0x4a34d0 in journal_remote_get_writer /work/build/../../src/systemd/src/journal-remote/journal-remote.c:136:21 #5 0x4a550f in get_source_for_fd /work/build/../../src/systemd/src/journal-remote/journal-remote.c:183:13 #6 0x4a46bd in journal_remote_add_source /work/build/../../src/systemd/src/journal-remote/journal-remote.c:235:13 #7 0x4a271c in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/fuzz/fuzz-journal-remote.c:36:9 #8 0x4f27cc in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/libfuzzer/FuzzerLoop.cpp:524:13 #9 0x4efa0b in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*) /src/libfuzzer/FuzzerLoop.cpp:448:3 #10 0x4f8e96 in fuzzer::Fuzzer::ReadAndExecuteSeedCorpora(std::__1::vector, std::__1::allocator >, fuzzer::fuzzer_allocator, std::__1::allocator > > > const&) /src/libfuzzer/FuzzerLoop.cpp:732:7 #11 0x4f9f73 in fuzzer::Fuzzer::Loop(std::__1::vector, std::__1::allocator >, fuzzer::fuzzer_allocator, std::__1::allocator > > > const&) /src/libfuzzer/FuzzerLoop.cpp:752:3 #12 0x4bf329 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/libfuzzer/FuzzerDriver.cpp:756:6 #13 0x4ac391 in main /src/libfuzzer/FuzzerMain.cpp:20:10 #14 0x7ff36d14982f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f) #15 0x41f9d8 in _start (/out/fuzz-journal-remote+0x41f9d8) Uninitialized value was stored to memory at #0 0x7ff36e61cd41 in sd_id128_randomize /work/build/../../src/systemd/src/libsystemd/sd-id128/sd-id128.c:288:16 #1 0x7ff36e685cec in journal_file_init_header /work/build/../../src/systemd/src/journal/journal-file.c:426:13 #2 0x7ff36e683a9d in journal_file_open /work/build/../../src/systemd/src/journal/journal-file.c:3333:21 #3 0x7ff36e68b8f6 in journal_file_open_reliably /work/build/../../src/systemd/src/journal/journal-file.c:3520:13 #4 0x4a3f35 in open_output /work/build/../../src/systemd/src/journal-remote/journal-remote.c:70:13 #5 0x4a34d0 in journal_remote_get_writer /work/build/../../src/systemd/src/journal-remote/journal-remote.c:136:21 #6 0x4a550f in get_source_for_fd /work/build/../../src/systemd/src/journal-remote/journal-remote.c:183:13 #7 0x4a46bd in journal_remote_add_source /work/build/../../src/systemd/src/journal-remote/journal-remote.c:235:13 #8 0x4a271c in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/fuzz/fuzz-journal-remote.c:36:9 #9 0x4f27cc in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/libfuzzer/FuzzerLoop.cpp:524:13 #10 0x4efa0b in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*) /src/libfuzzer/FuzzerLoop.cpp:448:3 #11 0x4f8e96 in fuzzer::Fuzzer::ReadAndExecuteSeedCorpora(std::__1::vector, std::__1::allocator >, fuzzer::fuzzer_allocator, std::__1::allocator > > > const&) /src/libfuzzer/FuzzerLoop.cpp:732:7 #12 0x4f9f73 in fuzzer::Fuzzer::Loop(std::__1::vector, std::__1::allocator >, fuzzer::fuzzer_allocator, std::__1::allocator > > > const&) /src/libfuzzer/FuzzerLoop.cpp:752:3 #13 0x4bf329 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/libfuzzer/FuzzerDriver.cpp:756:6 #14 0x4ac391 in main /src/libfuzzer/FuzzerMain.cpp:20:10 #15 0x7ff36d14982f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f) Uninitialized value was created by an allocation of 't' in the stack frame of function 'sd_id128_randomize' #0 0x7ff36e61cb00 in sd_id128_randomize /work/build/../../src/systemd/src/libsystemd/sd-id128/sd-id128.c:274 SUMMARY: MemorySanitizer: use-of-uninitialized-value /work/build/../../src/systemd/src/journal/journal-file.c:436:13 in journal_file_init_header Exiting MS: 0 ; base unit: 0000000000000000000000000000000000000000 artifact_prefix='./'; Test unit written to ./crash-847911777b3096783f4ee70a69ab6d28380c810b [vagrant@localhost oss-fuzz]$ sudo infra/helper.py check_build --sanitizer=memory systemd Running: docker run --rm -i --privileged -e FUZZING_ENGINE=libfuzzer -e SANITIZER=memory -v /home/vagrant/oss-fuzz/build/out/systemd:/out -t gcr.io/oss-fuzz-base/base-runner test_all INFO: performing bad build checks for /out/fuzz-dhcp-server. INFO: performing bad build checks for /out/fuzz-journal-remote. INFO: performing bad build checks for /out/fuzz-unit-file. INFO: performing bad build checks for /out/fuzz-dns-packet. 4 fuzzers total, 0 seem to be broken (0%). Check build passed. It's a false positive which is most likely caused by https://github.com/google/sanitizers/issues/852. I think it could be got around by avoiding `getrandom` when the code is compiled with `msan` --- src/basic/random-util.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/basic/random-util.c b/src/basic/random-util.c index 0750083b88541..03117c225e35f 100644 --- a/src/basic/random-util.c +++ b/src/basic/random-util.c @@ -46,7 +46,7 @@ int acquire_random_bytes(void *p, size_t n, bool high_quality_required) { * for us. */ /* Use the getrandom() syscall unless we know we don't have it. */ - if (have_syscall != 0) { + if (have_syscall != 0 && !HAS_FEATURE_MEMORY_SANITIZER) { r = getrandom(p, n, GRND_NONBLOCK); if (r > 0) { have_syscall = true;