From 6e9ac0a2e2a62449f0c1a89563f80b7bb71c6121 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 25 Nov 2017 14:42:10 -0500 Subject: [PATCH] Avoid formally-undefined use of memcpy() in hstoreUniquePairs(). hstoreUniquePairs() often called memcpy with equal source and destination pointers. Although this is almost surely harmless in practice, it's undefined according to the letter of the C standard. Some versions of valgrind will complain about it, and some versions of libc as well (cf. commit ad520ec4a). Tweak the code to avoid doing that. Noted by Tomas Vondra. Back-patch to all supported versions because of the hazard of libc assertions. Discussion: https://postgr.es/m/bf84d940-90d4-de91-19dd-612e011007f4@fuzzy.cz --- contrib/hstore/hstore_io.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/contrib/hstore/hstore_io.c b/contrib/hstore/hstore_io.c index 93206193916..cf6fd7c6aa5 100644 --- a/contrib/hstore/hstore_io.c +++ b/contrib/hstore/hstore_io.c @@ -339,7 +339,8 @@ hstoreUniquePairs(Pairs *a, int32 l, int32 *buflen) { *buflen += res->keylen + ((res->isnull) ? 0 : res->vallen); res++; - memcpy(res, ptr, sizeof(Pairs)); + if (res != ptr) + memcpy(res, ptr, sizeof(Pairs)); } ptr++;