Fix out-of-bound read in gtsvector_picksplit()

This could lead to an imprecise choice when splitting an index page of a
GiST index on a tsvector, deciding which entries should remain on the
old page and which entries should move to a new page.

This is wrong since tsearch2 has been moved into core with commit
140d4ebcb46e, so backpatch all the way down.  This error has been
spotted by valgrind.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/17950-6c80a8d2b94ec695@postgresql.org
Backpatch-through: 11

diff --git a/src/backend/utils/adt/tsgistidx.c b/src/backend/utils/adt/tsgistidx.c
index 2d9ecc4bfdc4d24bb3de6c2eb93e531d256bc1ff..a78de0889272070e2bed49a97a4e5a7e1429c564 100644 (file)
--- a/src/backend/utils/adt/tsgistidx.c
+++ b/src/backend/utils/adt/tsgistidx.c
@@ -751,7 +751,7 @@ gtsvector_picksplit(PG_FUNCTION_ARGS)
                size_alpha = 0;
            else
                size_alpha = SIGLENBIT - sizebitvec(
-                                                   (cache[j].allistrue) ? GETSIGN(datum_l) : GETSIGN(cache[j].sign)
+                                                   (cache[j].allistrue) ? GETSIGN(datum_l) : cache[j].sign
                    );
        }
        else
@@ -763,7 +763,7 @@ gtsvector_picksplit(PG_FUNCTION_ARGS)
                size_beta = 0;
            else
                size_beta = SIGLENBIT - sizebitvec(
-                                                  (cache[j].allistrue) ? GETSIGN(datum_r) : GETSIGN(cache[j].sign)
+                                                  (cache[j].allistrue) ? GETSIGN(datum_r) : cache[j].sign
                    );
        }
        else