Limit to_tsvector_byid's initial array allocation to something sane.

The initial estimate of the number of distinct ParsedWords is just
that: an estimate.  Don't let it exceed what palloc is willing to
allocate.  If in fact we need more entries, we'll eventually fail
trying to enlarge the array.  But if we don't, this allows success on
inputs that currently draw "invalid memory alloc request size".

Per bug #18080 from Uwe Binder.  Back-patch to all supported branches.

Discussion: https://postgr.es/m/18080-d5c5e58fef8c99b7@postgresql.org

diff --git a/src/backend/tsearch/to_tsany.c b/src/backend/tsearch/to_tsany.c
index 4b44b8564245396da8b05aad41bfe24186611399..e01f37583977f8fada1a4790d03d92feb18d5633 100644 (file)
--- a/src/backend/tsearch/to_tsany.c
+++ b/src/backend/tsearch/to_tsany.c
@@ -242,6 +242,8 @@ to_tsvector_byid(PG_FUNCTION_ARGS)
                                                                                                 * number */
        if (prs.lenwords < 2)
                prs.lenwords = 2;
+       else if (prs.lenwords > MaxAllocSize / sizeof(ParsedWord))
+               prs.lenwords = MaxAllocSize / sizeof(ParsedWord);
        prs.curwords = 0;
        prs.pos = 0;
        prs.words = (ParsedWord *) palloc(sizeof(ParsedWord) * prs.lenwords);