Arian van Putten
1ff2c33055
fluent-bit 3.2.7, 3.2.8 and 3.2.9 are segfaulting when used in combination with the systemd input. Lets revert to 3.2.6 for now. Upstream bug: https://github.com/fluent/fluent-bit/issues/10139 Note that fluent-bit-3.2.7 fixes two high CVEs which we are now reintroducing. However they are only exploitable if you are using the OpenTelemetry input or the Prometheus Remote Write input. OpenTelemetry input: [CVE-2024-50609](https://nvd.nist.gov/vuln/detail/CVE-2024-50609) Prometheus Remote Write input: [CVE-2024-50608](https://nvd.nist.gov/vuln/detail/CVE-2024-50608) The problem is as follows: 3.2.7 started vendoring a copy of `libzstd` in tree and statically linking against it. Also, the fluent-bit binary exports the symbols of static libraries it links against. This is a problem because `libzstd` gets `dlopen()`ed by `libsystemd` when enumerating the journal (as journal logs are zstd compressed). and `libzstd` in Nixpkgs is built with `-DZSTD_LEGACY_SUPPORT=0` which causes `struct ZSTD_DCtx` to be 16 bytes smaller than without this flag https://github.com/facebook/zstd/blob/dev/lib/decompress/zstd_decompress_internal.h#L183-L187 `libsystemd` calls [`sym_ZSTD_createDCtx()`](https://github.com/systemd/systemd/blob/1e79a2923364b65fc9f347884dd5b9b2087f6e32/src/basic/compress.c#L480) which calls the function pointer returned by `dlsym()` which is calling into the `libzstd` that comes with `nixpkgs` and thus allocates a struct that is 16 bytes smaller. Later then `sym_ZSTD_freeDCtx()` is called. However because fluent-bit has `zstd` in its global symbol table, any functions that `sym_ZSTD_freeDCtx()` calls will be calls to the functions in the vendored fluent-bit version of the library which expects the larger struct. This then causes enough heap corruption to cause a segfault. E.g. the subsequent calls to `ZSTD_clearDict(dctx)` and `ZSTD_customFree(dctx->inBuff)` in https://github.com/facebook/zstd/blob/dev/lib/decompress/zstd_decompress.c#L324 will be working on a struct that is 16 bytes smaller than the one that was allocated by `libsystemd` and will cause a segfault at some point and thus are probably modifying pieces of memory that they shouldn't (gdb) bt #0 0x00007f10e7e9916c in __pthread_kill_implementation () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 #1 0x00007f10e7e40e86 in raise () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 #2 0x00007f10e7e2893a in abort () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 #3 0x000000000046a938 in flb_signal_handler () #4 <signal handler called> #5 0x00007f10e7ea42b7 in unlink_chunk.isra () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 #6 0x00007f10e7ea45cd in _int_free_create_chunk () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 #7 0x00007f10e7ea5a1c in _int_free_merge_chunk () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 #8 0x00007f10e7ea5dc9 in _int_free () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 #9 0x00007f10e7ea8613 in free () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 #10 0x00007f10e80ad3b5 in ZSTD_freeDCtx () from /nix/store/wy0slah6yvchgra8nhp6vgrqa6ay72cq-zstd-1.5.6/lib/libzstd.so.1 #11 0x00007f10e8c90f6b in decompress_blob_zstd () from /nix/store/b2cfj7yk3wfg1jdwjzim7306hvsc5gnl-systemd-257.3/lib/libsystemd.so.0 #12 0x00007f10e8bf0efe in journal_file_data_payload () from /nix/store/b2cfj7yk3wfg1jdwjzim7306hvsc5gnl-systemd-257.3/lib/libsystemd.so.0 #13 0x00007f10e8c00f74 in sd_journal_enumerate_data () from /nix/store/b2cfj7yk3wfg1jdwjzim7306hvsc5gnl-systemd-257.3/lib/libsystemd.so.0 #14 0x00000000004eae2f in in_systemd_collect () #15 0x00000000004eb5a0 in in_systemd_collect_archive () #16 0x000000000047aa18 in flb_input_collector_fd () #17 0x0000000000495223 in flb_engine_start () #18 0x000000000046f304 in flb_lib_worker () #19 0x00007f10e7e972e3 in start_thread () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 #20 0x00007f10e7f1b2fc in __clone3 () from /nix/store/rmy663w9p7xb202rcln4jjzmvivznmz8-glibc-2.40-66/lib/libc.so.6 Reverts7310ab328bReverts4fbc6cf9c3
Nixpkgs is a collection of over 100,000 software packages that can be installed with the Nix package manager. It also implements NixOS, a purely-functional Linux distribution.
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