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 f4ddfc01059ece060c3296776ae56350b2fcc82d..15d754564e8d65ac183818fdb57f89758152afcb 100644 (file)
--- a/src/backend/tsearch/to_tsany.c
+++ b/src/backend/tsearch/to_tsany.c
@@ -252,6 +252,8 @@ 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);