fix segfault when input shorter than all patterns#6071
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ebernhardson wants to merge 1 commit intofacebook:masterfrom
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fix segfault when input shorter than all patterns#6071ebernhardson wants to merge 1 commit intofacebook:masterfrom
ebernhardson wants to merge 1 commit intofacebook:masterfrom
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This pull request has been imported into Phabricator, and discussion and review of the diff will take place at https://reviews.facebook.net/D44973 |
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Reproduction case for the crash that this patch fixes: <?php
$map = array(
'ﭐ' => 'ٱ', 'ﭑ' => 'ٱ', 'ﭒ' => 'ٻ', 'ﭓ' => 'ٻ', 'ﭔ' => 'ٻ', 'ﭕ' => 'ٻ', 'ﭖ' => 'پ',
'ﭗ' => 'پ', 'ﭘ' => 'پ', 'ﭙ' => 'پ', 'ﭚ' => 'ڀ', 'ﭛ' => 'ڀ', 'ﭜ' => 'ڀ', 'ﭝ' => 'ڀ',
'ﭞ' => 'ٺ', 'ﭟ' => 'ٺ', 'ﭠ' => 'ٺ', 'ﭡ' => 'ٺ', 'ﭢ' => 'ٿ', 'ﭣ' => 'ٿ', 'ﭤ' => 'ٿ',
'ﭥ' => 'ٿ', 'ﭦ' => 'ٹ', 'ﭧ' => 'ٹ', 'ﭨ' => 'ٹ', 'ﭩ' => 'ٹ', 'ﭪ' => 'ڤ', 'ﭫ' => 'ڤ',
'ﭬ' => 'ڤ', 'ﭭ' => 'ڤ', 'ﭮ' => 'ڦ', 'ﭯ' => 'ڦ', 'ﭰ' => 'ڦ', 'ﭱ' => 'ڦ', 'ﭲ' => 'ڄ',
'ﭳ' => 'ڄ', 'ﭴ' => 'ڄ', 'ﭵ' => 'ڄ', 'ﭶ' => 'ڃ', 'ﭷ' => 'ڃ', 'ﭸ' => 'ڃ', 'ﭹ' => 'ڃ',
'ﭺ' => 'چ', 'ﭻ' => 'چ', 'ﭼ' => 'چ', 'ﭽ' => 'چ', 'ﭾ' => 'ڇ', 'ﭿ' => 'ڇ', 'ﮀ' => 'ڇ',
'ﮁ' => 'ڇ', 'ﮂ' => 'ڍ', 'ﮃ' => 'ڍ', 'ﮄ' => 'ڌ', 'ﮅ' => 'ڌ', 'ﮆ' => 'ڎ', 'ﮇ' => 'ڎ',
'ﮈ' => 'ڈ', 'ﮉ' => 'ڈ', 'ﮊ' => 'ژ', 'ﮋ' => 'ژ', 'ﮌ' => 'ڑ', 'ﮍ' => 'ڑ', 'ﮎ' => 'ک',
'ﮏ' => 'ک', 'ﮐ' => 'ک',
);
strtr( 'ab', $map ); |
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apologies for not finishing this up yet, still seeing an occasional crash in this code in prod and have not traced it down yet. |
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We close pull requests after changes are requested on phabricator for > 1 week. Will re-open when changes are made. |
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Author is coming back to this, per discussion on #6384 |
When the input string is shorter than the shortest input pattern the last position to visit is set to a negative, which due to the unsigned nature rolls over to a very big number. Fix short circuits and returns input string when all patterns are longer than the input string. The LRU cache is holding onto StringData between requests through the PatAndRepl class, but StringData uses the request-local allocator. To ensure the patterns and replacements survive across requests they are now copied into a std::string. Additionally this included a potential race condition under concurrency. initTables() could be running in one thread when the WuManberReplacement is pulled from the LRU cache. This second execution could start running the replacement before initTables() has completed. The class has been adjusted so it can be declared const at construction and does not change its internal state.
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Summary: When the input string is shorter than the shortest input pattern the last position to visit is set to -1. Patch short circuits and returns input string when all patterns are longer than the input string. Closes #6071 Reviewed By: jwatzman Differential Revision: D2367627 fb-gh-sync-id: 704ab038e68145916460c890bf6522dd62910af8
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When the input string is shorter than the shortest input
pattern the last position to visit is set to -1. Patch
short circuits and returns input string when all patterns
are longer than the input string.