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 6baee8e1558881a083da0b86756cf3349092f940..d9619c576e7beed1b593d3db9455f467af631873 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);