Hi Hackers,
ALTER SUBSCRIPTION ... REFRESH PUBLICATION may crash if a
subscribed table (or sequence) is dropped concurrently.
In check_publications_origin_tables(), the function iterates over
subrel_local_oids without holding locks on the individual relations.
If a table is dropped by another session between when the OID list was
collected and when get_rel_name() is called, it returns NULL. That
NULL is then passed to quote_literal_cstr(), which dereferences it
unconditionally, causing a segfault. The same pattern exists in
check_publications_origin_sequences() as well.
Attached a patch to fix this by doing a null check after get_rel_name() and
get_namespace_name(), and skip the relation if it's gone.
Thanks,
Satya
