From cfe4b5c4aaa0d86f9d98095515ae6582a053cc47 Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas@erlang.org>
Date: Mon, 27 Feb 2017 10:11:47 +0100
Subject: erts: Fix emasculation of binaries in port_control

This fixes a bug introduced in 3671dd2d
---
 erts/emulator/beam/io.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

(limited to 'erts')

diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index 9bf29ee230..38e403d91a 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -4889,10 +4889,18 @@ erts_port_control(Process* c_p,
 	    copy = 1;
 	else {
             ProcBin *pb = (ProcBin *) ebinp;
+            int offset = bufp - pb->val->orig_bytes;
 
-            if (pb->flags)
+	    ASSERT(pb->val->orig_bytes <= bufp
+		   && bufp + size <= pb->val->orig_bytes + pb->val->orig_size);
+
+            if (pb->flags) {
                 erts_emasculate_writable_binary(pb);
 
+                /* The procbin may have been reallocated, so update bufp */
+                bufp = pb->val->orig_bytes + offset;
+            }
+
 	    binp = pb->val;
 	    ASSERT(bufp <= bufp + size);
 	    ASSERT(binp->orig_bytes <= bufp
-- 
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