On Mon, Apr 1, 2024 at 7:36 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > Coverity complained about what you did in RelationParseRelOptions > in c95c25f9a: > > *** CID 1595992: Null pointer dereferences (FORWARD_NULL) > /srv/coverity/git/pgsql-git/postgresql/src/backend/utils/cache/relcache.c: > 499 in RelationParseRelOptions() > 493 > 494 /* > 495 * Fetch reloptions from tuple; have to use a hardwired > descriptor because > 496 * we might not have any other for pg_class yet (consider > executing this > 497 * code for pg_class itself) > 498 */ > >>> CID 1595992: Null pointer dereferences (FORWARD_NULL) > >>> Passing null pointer "tableam" to "extractRelOptions", which > >>> dereferences it. > 499 options = extractRelOptions(tuple, GetPgClassDescriptor(), > 500 > tableam, amoptsfn); > 501 > > I see that extractRelOptions only uses the tableam argument for some > relkinds, and RelationParseRelOptions does set it up for those > relkinds --- but Coverity's complaint isn't without merit, because > those two switch statements are looking at *different copies of the > relkind*, which in theory could be different. This all seems quite > messy and poorly factored. Can't we do better? Why do we need to > involve two copies of allegedly the same pg_class tuple, anyhow?
I wasn't registered at Coverity yet. Now I've registered and am waiting for approval to access the PostgreSQL analysis data. I wonder why Coverity complains about tableam, but not amoptsfn. Their usage patterns are very similar. It appears that relation->rd_rel isn't the full copy of pg_class tuple (see AllocateRelationDesc). RelationParseRelOptions() is going to update relation->rd_options, and thus needs a full pg_class tuple to fetch options out of it. However, it is really unnecessary to access both tuples at the same time. We can use a full tuple, not relation->rd_rel, in both cases. See the attached patch. ------ Regards, Alexander Korotkov
fix-RelationParseRelOptions-Coverity-complain.patch
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