[3.13] gh-138223: Fix Infinite loop in email._header_value_parser._fold_mime_parameters when parameter names are too long (GH-138223) #138227
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… parameter keys The infinite loop occurred in _fold_mime_parameters() when processing MIME parameters with very long keys (≥64 characters) during RFC 2231 encoding. The issue was in two locations: 1. In email._header_value_parser._fold_mime_parameters(): - Replace infinite while True: loop with while splitpoint > 1: - Ensure splitpoint is always at least 1 to prevent getting stuck - Add fallback logic to force minimal splits when values cannot fit 2. In email.header._ValueFormatter._append_chunk(): - Add safety check for extremely long strings that cannot be split - Force line breaks when no suitable split points are found - Prevent infinite loops in header folding for edge cases This fixes GitHub issue python#138223 where add_attachment() with long parameter keys would cause as_string() to hang indefinitely during MIME parameter folding and header processing.
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… parameter keys The infinite loop occurred in _fold_mime_parameters() when processing MIME parameters with very long keys (64 characters) during RFC 2231 encoding. The issue was in two locations: 1. In email._header_value_parser._fold_mime_parameters(): - Replace infinite 'while True:' loop with 'while splitpoint > 1:' - Ensure splitpoint is always at least 1 to prevent getting stuck - Add fallback logic to force minimal splits when values cannot fit 2. In email.header._ValueFormatter._append_chunk(): - Add safety check for extremely long strings that cannot be split - Force line breaks when no suitable split points are found - Prevent infinite loops in header folding for edge cases This fixes GitHub issue python#138223 where add_attachment() with long parameter keys would cause as_string() to hang indefinitely during MIME parameter folding and header processing.
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Please create the PR against main, changing it will result in #138226. |
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Before jumping to a PR, please read https://devguide.python.org/getting-started/pull-request-lifecycle carefully. In addition, please check the RFC for what to do. |
Hi Stan, thank you for your review! Should I create this PR against main other than 3.13? |
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Please see Benedikts message. It's the branch "main" |
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-- Replaced while True: with while splitpoint > 1: to prevent infinite loops
-- Added splitpoint = max(1, splitpoint) to ensure splitpoint is always at least 1
-- Added fallback logic to force a minimal split if splitpoint becomes too small
-- Fixed the outer while value: loop to ensure progress is always made
-- Added force-split logic to handle extremely long strings that can't be split by standard methods
-- Prevents infinite loops when no suitable split points are found
email._header_value_parser._fold_mime_parameterswhen parameter names are too long #138223