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MDEV-17005 ASAN heap-use-after-free in innobase_get_computed_value
This is the race between DELETE and INSERT (or other any two operations accessing to the table). What should happen in good case: 1. ALTER TABLE is issued. vc_templ->default_rec is initialized with temporary share's default_fields 2. temporary share is freed, but datadict is still there, with garbage in vc_templ->default_rec 3. DELETE is issued. It is first after ALTER TABLE finished. 4. ha_innobase::open() is called, ib_table->get_ref_count() should be one 5. we reinitialize vc_templ, so no garbage anymore What actually happens: 3. DELETE is issued. 4. ha_innobase::open() is called and ib_table->get_ref_count() is 1 5. INSERT (or SELECT etc.) is issued in parallel 6. ha_innobase::open() is called and ib_table->get_ref_count() is 1 7. we check ib_table->get_ref_count() and it is 2 in both threads when we want reinitialize vc_templ 8. garbage is there Fix: * Do not store pointers to SHARE memory in table dict, copy it instead. * But then we don't need to refresh it each time when refcount=1.
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