From 540ac7cea919623f691b20892ccc50e5e33b5009 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Tue, 13 May 2014 14:16:28 +0300 Subject: [PATCH] Initialize padding bytes in btree_gist varbit support. The code expands a varbit gist leaf key to a node key by copying the bit data twice in a varlen datum, as both the lower and upper key. The lower key was expanded to INTALIGN size, but the padding bytes were not initialized. That's a problem because when the lower/upper keys are compared, the padding bytes are used compared too, when the values are otherwise equal. That could lead to incorrect query results. REINDEX is advised for any btree_gist indexes on bit or bit varying data type, to fix any garbage padding bytes on disk. Per Valgrind, reported by Andres Freund. Backpatch to all supported versions. --- contrib/btree_gist/btree_bit.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/contrib/btree_gist/btree_bit.c b/contrib/btree_gist/btree_bit.c index edf75e06842..76297515c5e 100644 --- a/contrib/btree_gist/btree_bit.c +++ b/contrib/btree_gist/btree_bit.c @@ -75,10 +75,14 @@ static bytea * gbt_bit_xfrm(bytea *leaf) { bytea *out = leaf; - int s = INTALIGN(VARBITBYTES(leaf) + VARHDRSZ); - - out = palloc(s); - SET_VARSIZE(out, s); + int sz = VARBITBYTES(leaf) + VARHDRSZ; + int padded_sz = INTALIGN(sz); + + out = (bytea *) palloc(padded_sz); + /* initialize the padding bytes to zero */ + while (sz < padded_sz) + ((char *) out)[sz++] = 0; + SET_VARSIZE(out, padded_sz); memcpy((void *) VARDATA(out), (void *) VARBITS(leaf), VARBITBYTES(leaf)); return out; } -- 2.39.5