libfmt:fuzzer_named_arg: Stack-buffer-underflow in fmt::v6::basic_format_args<fmt::v6::basic_format_context<std::__1::back_insert_i

2020-04-19T23:03:44
ID OSSFUZZ-21794
Type ossfuzz
Reporter Google
Modified 2020-05-24T20:01:52

Description

Detailed Report: https://oss-fuzz.com/testcase?key=5747676286287872

Project: libfmt Fuzzing Engine: libFuzzer Fuzz Target: fuzzer_named_arg Job Type: libfuzzer_asan_libfmt Platform Id: linux

Crash Type: Stack-buffer-underflow READ 16 Crash Address: 0x7f200d9a6110 Crash State: fmt::v6::basic_format_args<fmt::v6::basic_format_context<std::__1::back_insert_i fmt::v6::basic_format_args<fmt::v6::basic_format_context<std::__1::back_insert_i fmt::v6::basic_format_context<std::__1::back_insert_iterator<fmt::v6::internal::

Sanitizer: address (ASAN)

Regressed: https://oss-fuzz.com/revisions?job=libfuzzer_asan_libfmt&range=202004142048:202004150231

Reproducer Testcase: https://oss-fuzz.com/download?testcase_id=5747676286287872

Issue filed automatically.

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This bug is subject to a 90 day disclosure deadline. If 90 days elapse without an upstream patch, then the bug report will automatically become visible to the public.