QUIC: fixed accessing a released stream. #413
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It doesn't seem to prevent recursive closure as in "request stream close -> decoder stream close". |
pluknet
approved these changes
Dec 27, 2024
While trying to close a stream in ngx_quic_close_streams() by calling its read event handler, the next stream saved prior to that could be destroyed recursively. This caused a segfault while trying to access the next stream. The way the next stream could be destroyed in HTTP/3 is the following. A request stream read event handler ngx_http_request_handler() could end up calling ngx_http_v3_send_cancel_stream() to report a cancelled request stream in the decoder stream. If sending stream cancellation decoder instruction fails for any reason, and the decoder stream is the next in order after the request stream, the issue is triggered. The fix is to postpone calling read event handlers for all streams being closed to avoid closing a released stream.
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While trying to close a stream in ngx_quic_close_streams() by calling its read event handler, the next stream saved prior to that could be destroyed recursively. This caused a segfault while trying to access the next stream.
The way the next stream could be destroyed in HTTP/3 is the following. A request stream read event handler ngx_http_request_handler() could end up calling ngx_http_v3_send_cancel_stream() to report a cancelled request stream in the decoder stream. If sending stream cancellation decoder instruction fails for any reason, and the decoder stream is the next in order after the request stream, the issue is triggered.
The fix is to postpone calling read event handlers for all streams being closed to avoid recursive closures.
Fixes #369.