From: Ian Lance Taylor <iant@golang.org>
Date: Fri, 7 Dec 2018 15:25:50 +0000 (-0800)
Subject: cmd/internal/obj/s390x: don't crash on invalid instruction
X-Git-Tag: go1.12beta1~139
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=e546ef123e6e3a28dc7722fb6bbf1161b7024163;p=gostls13.git

cmd/internal/obj/s390x: don't crash on invalid instruction

I didn't bother with a test as there doesn't seem to be an existing
framework for testing assembler failures, and tests for invalid code
aren't all that interesting.

Fixes #26700

Change-Id: I719410d83527802a09b9d38625954fdb36a3c0f7
Reviewed-on: https://go-review.googlesource.com/c/153177
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---

diff --git a/src/cmd/internal/obj/s390x/asmz.go b/src/cmd/internal/obj/s390x/asmz.go
index 4e43d27790..7d49103be6 100644
--- a/src/cmd/internal/obj/s390x/asmz.go
+++ b/src/cmd/internal/obj/s390x/asmz.go
@@ -2618,6 +2618,10 @@ func (c *ctxtz) branchMask(p *obj.Prog) uint32 {
 func (c *ctxtz) asmout(p *obj.Prog, asm *[]byte) {
 	o := c.oplook(p)
 
+	if o == nil {
+		return
+	}
+
 	switch o.type_ {
 	default:
 		c.ctxt.Diag("unknown type %d", o.type_)