From 36646d3aff0cf6ff9f26033e38808d23e27426e8 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 3 Sep 2016 13:28:53 -0400 Subject: [PATCH] Fix corrupt GIN_SEGMENT_ADDITEMS WAL records on big-endian hardware. computeLeafRecompressWALData() tried to produce a uint16 WAL log field by memcpy'ing the first two bytes of an int-sized variable. That accidentally works on little-endian hardware, but not at all on big-endian. Replay then thinks it's looking at an ADDITEMS action with zero entries, and reads the first two bytes of the first TID therein as the next segno/action, typically leading to "unexpected GIN leaf action" errors during replay. Even if replay failed to crash, the resulting GIN index page would surely be incorrect. To fix, just declare the variable as uint16 instead. Per bug #14295 from Spencer Thomason (much thanks to Spencer for turning his problem into a self-contained test case). This likely also explains a previous report of the same symptom from Bernd Helmle. Back-patch to 9.4 where the problem was introduced (by commit 14d02f0bb). Discussion: <20160826072658.15676.7628@wrigleys.postgresql.org> Possible-Report: <2DA7350F7296B2A142272901@eje.land.credativ.lan> --- src/backend/access/gin/gindatapage.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/backend/access/gin/gindatapage.c b/src/backend/access/gin/gindatapage.c index 97c8bf78e7..276376a6f1 100644 --- a/src/backend/access/gin/gindatapage.c +++ b/src/backend/access/gin/gindatapage.c @@ -86,7 +86,7 @@ typedef struct char action; ItemPointerData *modifieditems; - int nmodifieditems; + uint16 nmodifieditems; /* * The following fields represent the items in this segment. If 'items' is -- 2.40.0