decode_opentelemetry: guard NULL fqname and label name in compute_metric_hash#265
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edsiper merged 2 commits intofluent:masterfrom May 4, 2026
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…d compute_metric_hash decode_data_point_labels falls into its else branch for unrecognised AnyValue.value_case values (e.g. NOT_SET = 0) and passes NULL to append_new_metric_label_value, leaving label->name as NULL. Any encoder calling cfl_sds_len(label->name) -- including cmt_encode_text and cmt_encode_splunk_hec -- then crashes. Fix: store "" (empty string) in the unrecognised-value fallback, consistent with STRING_VALUE_STRINDEX. Also extend the early-return guard in compute_metric_hash to cover map->opts == NULL and map->opts->fqname == NULL (matching get_or_create_metric_metadata_context), and skip NULL label names in the hash loop, for defence in depth. Signed-off-by: Enoque Duarte <enoquefcd@gmail.com>
…Value Add otlp_null_label_histogram.bin -- a serialised ExportMetricsServiceRequest with one Histogram data point whose sole attribute has AnyValue.value_case = NOT_SET. The test opentelemetry_histogram_null_label_no_crash verifies the decoder returns CMT_DECODE_OPENTELEMETRY_SUCCESS rather than exiting with SIGSEGV. Signed-off-by: Enoque Duarte <enoquefcd@gmail.com>
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compute_metric_hashdereferencesmap->opts->fqnameandlabel_value->namewithout NULL checks while its peerget_or_create_metric_metadata_context, called immediately after from the same caller, already guardsmap->optsandmap->opts->fqname. The unguarded path is reachable from real OTLP/HTTP histogram payloads —cfl_sds_len(NULL)segfaults the worker.Reported and reproduced via fluent/fluent-bit#11764 with Quarkus 3.32.x clients pushing histograms over OTLP/HTTP. Stack trace:
Root cause
decode_data_point_labelsfalls into itselsebranch for unrecognisedAnyValue.value_casevalues (e.g.NOT_SET = 0) and passesNULLtoappend_new_metric_label_value.create_label(NULL, …)leaveslabel->nameas NULL, which crashes any encoder callingcfl_sds_len(label->name)— not onlycompute_metric_hashbut alsocmt_encode_textandcmt_encode_splunk_hec.Changes
decode_data_point_labels: store""(empty string) in the unrecognised-value fallback, consistent withSTRING_VALUE_STRINDEX. Prevents NULL from enteringmetric->labels.compute_metric_hash: extend the early-return guard to covermap->opts == NULL || map->opts->fqname == NULL(matchingget_or_create_metric_metadata_context), and skip NULL label names in the hash loop — defence in depth.Regression test
tests/data/otlp_null_label_histogram.bin— a serialisedExportMetricsServiceRequestwith one Histogram data point whose sole attribute hasAnyValue.value_case = NOT_SET. Without this fix the test exits SIGSEGV (signal 11); with it,CMT_DECODE_OPENTELEMETRY_SUCCESS.ctest --test-dir build -R cmt-test-opentelemetry --output-on-failure # or ./build/tests/cmt-test-opentelemetry opentelemetry_histogram_null_label_no_crash