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 edeffacc2d75a66a675613aa0f8b3757ef5c8deb..361aa997daafa0ed87cbe6d92fe1cfaf2868d324 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);