From: Niko Tyni <ntyni@debian.org>
Subject: Fix stack pointer corruption in pp_concat() with 'use encoding'
Bug-Debian: http://bugs.debian.org/596105
Bug: http://rt.perl.org/rt3/Ticket/Display.html?id=78674
Origin: upstream, http://perl5.git.perl.org/perl.git/commit/e3393f51d48d8b790e26324eb0336fac9689fa46

If the stack is reallocated during pp_concat() and 'use encoding' in
effect, the stack pointer gets corrupted, causing memory allocation bugs
and the like.

---
 pp_hot.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/pp_hot.c b/pp_hot.c
index 3371e88..e9cccf3 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -271,6 +271,8 @@ PP(pp_concat)
 	rbyte = !DO_UTF8(right);
     }
     if (lbyte != rbyte) {
+	/* sv_utf8_upgrade_nomg() may reallocate the stack */
+	PUTBACK;
 	if (lbyte)
 	    sv_utf8_upgrade_nomg(TARG);
 	else {
@@ -279,6 +281,7 @@ PP(pp_concat)
 	    sv_utf8_upgrade_nomg(right);
 	    rpv = SvPV_const(right, rlen);
 	}
+	SPAGAIN;
     }
     sv_catpvn_nomg(TARG, rpv, rlen);
 
-- 
tg: (c823880..) fixes/concat-stack-corruption (depends on: upstream)