Fix default reporter use after free#2248
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CreateDefaultDisplayReporter() cached its reporter in a function-local static and returned that pointer. But the returned pointer is owned by the caller: RunSpecifiedBenchmarks() wraps it in a std::unique_ptr that frees it when the call returns. The first call therefore freed the static reporter, and the next call returned the same, now-dangling pointer, which was dereferenced when setting up the output streams -- a heap-use-after-free reachable by simply calling RunSpecifiedBenchmarks more than once (reported via fuzzing on the no-match filter path). Return a fresh, caller-owned reporter on every call. Add default_display_reporter_test, which holds two reporters from two calls alive at once and asserts they are distinct objects; it fails on the old static implementation and passes with this fix. Verified locally with g++ 15.2; benchmark_test and memory_manager_test still pass. Signed-off-by: devtejasx <tejasnagmote520@gmail.com>
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Rebased — the branch is now a single commit (f1f1485) on top of current main containing only the 4-file fix. On the |
dmah42
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Jul 16, 2026
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| BENCHMARK_EXPORT int32_t GetBenchmarkVerbosity(); | ||
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| // Creates the display reporter selected by --benchmark_format. Returns a |
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if the caller is meant to own the returned type, then we should be returning a unique_ptr.
https://google.github.io/styleguide/cppguide.html#Ownership_and_Smart_Pointers
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Fixes #2240.
Root cause: CreateDefaultDisplayReporter() cached the reporter it creates in a function-local static, while every caller owns and frees the returned pointer (RunSpecifiedBenchmarks() wraps it in a std::unique_ptr). The first call therefore freed the cached object, and every later call returned a dangling pointer, producing the heap-use-after-free reported in #2240.
Fix: return a fresh, caller-owned reporter on every call, and document the ownership contract at the public declaration in benchmark_api.h.
Testing:
Note: the branch was rebased onto current main to remove an unrelated commit that was previously included by mistake.
AI disclosure (per AGENTS.md): this change was developed with AI assistance (Anthropic's Claude).