fix(ico,png): avoid leaking error string across png_chunk_error longjmp#5289
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lgritz wants to merge 1 commit into
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fix(ico,png): avoid leaking error string across png_chunk_error longjmp#5289lgritz wants to merge 1 commit into
lgritz wants to merge 1 commit into
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PngReadCallback passed icoinput->geterror(false).c_str() to png_chunk_error() when a PNG read failed. png_chunk_error() does not return -- it longjmps back to libpng's setjmp point, which skips C++ destructors, so the temporary std::string returned by geterror() was never freed. The fuzzer surfaced this as a small, intermittent leak (a few KB across hundreds of thousands of runs). Copy the message into a plain stack buffer (no destructor) before calling png_chunk_error, so nothing heap-allocated is alive across the longjmp. Assisted-by: Claude Code / Claude Opus 4.8 Signed-off-by: Larry Gritz <lg@larrygritz.com>
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PngReadCallback passed input->geterror(false).c_str() to png_chunk_error() when a PNG read failed. png_chunk_error() does not return -- it longjmp's back to libpng's setjmp point, which skips C++ destructors, so the temporary std::string returned by geterror() was never freed. The fuzzer surfaced this as a small, intermittent leak (a few KB across hundreds of thousands of runs).
Copy the message into a plain stack buffer (no destructor) before calling png_chunk_error, so nothing heap-allocated is alive across the longjmp.
Assisted-by: Claude Code / Claude Opus 4.8