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-rw-r--r--test/fixedbugs/issue40629.go69
1 files changed, 69 insertions, 0 deletions
diff --git a/test/fixedbugs/issue40629.go b/test/fixedbugs/issue40629.go
new file mode 100644
index 0000000..c6ef408
--- /dev/null
+++ b/test/fixedbugs/issue40629.go
@@ -0,0 +1,69 @@
+// run
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+const N = 40
+
+func main() {
+ var x [N]int // stack-allocated memory
+ for i := range x {
+ x[i] = 0x999
+ }
+
+ // This defer checks to see if x is uncorrupted.
+ defer func(p *[N]int) {
+ recover()
+ for i := range p {
+ if p[i] != 0x999 {
+ for j := range p {
+ fmt.Printf("p[%d]=0x%x\n", j, p[j])
+ }
+ panic("corrupted stack variable")
+ }
+ }
+ }(&x)
+
+ // This defer starts a new goroutine, which will (hopefully)
+ // overwrite x on the garbage stack.
+ defer func() {
+ c := make(chan bool)
+ go func() {
+ useStack(1000)
+ c <- true
+ }()
+ <-c
+
+ }()
+
+ // This defer causes a stack copy.
+ // The old stack is now garbage.
+ defer func() {
+ useStack(1000)
+ }()
+
+ // Trigger a segfault.
+ *g = 0
+
+ // Make the return statement unreachable.
+ // That makes the stack map at the deferreturn call empty.
+ // In particular, the argument to the first defer is not
+ // marked as a pointer, so it doesn't get adjusted
+ // during the stack copy.
+ for {
+ }
+}
+
+var g *int64
+
+func useStack(n int) {
+ if n == 0 {
+ return
+ }
+ useStack(n - 1)
+}