runtime: impose stack size limit

The goal is to stop only those programs that would keep
going and run the machine out of memory, but before they do that.
1 GB on 64-bit, 250 MB on 32-bit.
That seems implausibly large, and it can be adjusted.

Fixes #2556.
Fixes #4494.
Fixes #5173.

R=khr, r, dvyukov
CC=golang-dev
https://golang.org/cl/12541052

1 files changed, 15 insertions, 0 deletions

diff --git a/src/pkg/runtime/debug/garbage.go b/src/pkg/runtime/debug/garbage.go
index 8f30264264..3658feaaf8 100644
--- a/src/pkg/runtime/debug/garbage.go
+++ b/src/pkg/runtime/debug/garbage.go
@@ -24,6 +24,7 @@ func readGCStats(*[]time.Duration)
 func enableGC(bool) bool
 func setGCPercent(int) int
 func freeOSMemory()
+func setMaxStack(int) int
 
 // ReadGCStats reads statistics about garbage collection into stats.
 // The number of entries in the pause history is system-dependent;
@@ -99,3 +100,17 @@ func SetGCPercent(percent int) int {
 func FreeOSMemory() {
 	freeOSMemory()
 }
+
+// SetMaxStack sets the maximum amount of memory that
+// can be used by a single goroutine stack.
+// If any goroutine exceeds this limit while growing its stack,
+// the program crashes.
+// SetMaxStack returns the previous setting.
+// The initial setting is 1 GB on 64-bit systems, 250 MB on 32-bit systems.
+//
+// SetMaxStack is useful mainly for limiting the damage done by
+// goroutines that enter an infinite recursion. It only limits future
+// stack growth.
+func SetMaxStack(bytes int) int {
+	return setMaxStack(bytes)
+}