Guard HTTP/2 frame sequence lookahead#364
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bneradt merged 1 commit intoyahoo:masterfrom Mar 17, 2026
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H2Session::write() pops the current frame from the stream frame sequence and then immediately looks at the next entry to decide which flags to set. When the current frame is the last queued frame, that unconditional front() call reads past the end of the deque and aborts proxy-verifier with a std::deque::front() assertion. Treat an empty post-pop frame sequence as having no next frame by using H2Frame::INVALID for the lookahead value. That preserves the existing flag selection logic while avoiding the invalid deque access on the final frame.
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H2Session::write() pops the current frame from the stream frame sequence and then immediately looks at the next entry to decide which flags to set. When the current frame is the last queued frame, that unconditional front() call reads past the end of the deque and aborts proxy-verifier with a std::deque::front() assertion.
Treat an empty post-pop frame sequence as having no next frame by using H2Frame::INVALID for the lookahead value. That preserves the existing flag selection logic while avoiding the invalid deque access on the final frame.
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