memtx: fix use-after-free of successor in tree_iterator_start#7759
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alyapunov merged 1 commit intotarantool:masterfrom Nov 30, 2022
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drewdzzz
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Oct 31, 2022
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The patch solves the set problems, but I am concerned about the current development vector - some methods categorically cannot call GC, and some methods on the contrary can do it implicitly (for example, gap trackers now should not call GC, but all other trackers can), and most importantly - during the process of development and support of transaction manager we must ensure that methods without GC do not call methods with it. I believe we need to redesign the transaction manager garbage collection system. The easiest option is to make ALL GC calls explicit.
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We assumed that the successor tuple's story could not get garbage collected on clarify of result tuple in `tree_iterator_start`, since they coincide in case of regular iterators. But this is not the case for reverse iterators: the result tuple is of-by-one from the successor, which means the successor's story can get garbage collected along with the tuple itself getting deleted, leading to use-after-free of successor: remove garbage collection from `memtx_tx_tuple_clarify` and call it manually. The crash in tarantool#7756 revealed that the `put` in transaction manager's story hash table was performed incorrectly: fix it and add an assertion that nothing was replaced. Closes tarantool#7755 Closes tarantool#7756 NO_DOC=bugfix
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alyapunov
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Nov 29, 2022
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Backported to 2.10. |
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We assumed that the successor tuple's story could not get garbage collected on clarify of result tuple in
tree_iterator_start, since they coincide in case of regular iterators. But this is not the case for reverse iterators: the result tuple is of-by-one from the successor, which means the successor's story can get garbage collected along with the tuple itself getting deleted, leading to use-after-free of successor: remove garbage collection frommemtx_tx_tuple_clarifyand call it manually.The crash in #7756 revealed that the
putin transaction manager's story hash table was performed incorrectly: fix it and add an assertion that nothing was replaced.Closes #7755
Closes #7756