From c7b9bd745642677c8d4b3b76803a39b4e50b4d81 Mon Sep 17 00:00:00 2001 From: Robert Griesemer Date: Fri, 15 Jul 2016 16:46:50 -0700 Subject: cmd/compile: don't crash when exporting self-recursive interfaces For #16369. Change-Id: I4c9f5a66b95558adcc1bcface164b9b2b4382d2f Reviewed-on: https://go-review.googlesource.com/24979 Reviewed-by: Alan Donovan --- src/cmd/compile/internal/gc/bexport.go | 33 ++++++++++++++++++++++++++++++++- src/go/types/stdlib_test.go | 1 + test/fixedbugs/issue16369.go | 13 +++++++++++++ 3 files changed, 46 insertions(+), 1 deletion(-) create mode 100644 test/fixedbugs/issue16369.go diff --git a/src/cmd/compile/internal/gc/bexport.go b/src/cmd/compile/internal/gc/bexport.go index 38e035edc8..4c28a68443 100644 --- a/src/cmd/compile/internal/gc/bexport.go +++ b/src/cmd/compile/internal/gc/bexport.go @@ -197,6 +197,9 @@ type exporter struct { written int // bytes written indent int // for p.trace trace bool + + // work-around for issue #16369 only + nesting int // amount of "nesting" of interface types } // export writes the exportlist for localpkg to out and returns the number of bytes written. @@ -790,11 +793,39 @@ func (p *exporter) typ(t *Type) { case TINTER: p.tag(interfaceTag) - // gc doesn't separate between embedded interfaces // and methods declared explicitly with an interface p.int(0) // no embedded interfaces + + // Because the compiler flattens interfaces containing + // embedded interfaces, it is possible to create interface + // types that recur through an unnamed type. + // If trackAllTypes is disabled, such recursion is not + // detected, leading to a stack overflow during export + // (issue #16369). + // As a crude work-around we terminate deep recursion + // through interface types with an empty interface and + // report an error. + // This will catch endless recursion, but is unlikely + // to trigger for valid, deeply nested types given the + // high threshold. + // It would be ok to continue without reporting an error + // since the export format is valid. But a subsequent + // import would import an incorrect type. The textual + // exporter does not report an error but importing the + // resulting package will lead to a syntax error during + // import. + // TODO(gri) remove this once we have a permanent fix + // for the issue. + if p.nesting > 100 { + p.int(0) // 0 methods to indicate empty interface + yyerrorl(t.Lineno, "cannot export unnamed recursive interface") + break + } + + p.nesting++ p.methodList(t) + p.nesting-- case TMAP: p.tag(mapTag) diff --git a/src/go/types/stdlib_test.go b/src/go/types/stdlib_test.go index bd5afafe39..1c6d7b5299 100644 --- a/src/go/types/stdlib_test.go +++ b/src/go/types/stdlib_test.go @@ -156,6 +156,7 @@ func TestStdFixed(t *testing.T) { "issue7746.go", // large constants - consumes too much memory "issue11362.go", // canonical import path check "issue15002.go", // uses Mmap; testTestDir should consult build tags + "issue16369.go", // go/types handles this correctly - not an issue ) } diff --git a/test/fixedbugs/issue16369.go b/test/fixedbugs/issue16369.go new file mode 100644 index 0000000000..bd03fbc6c9 --- /dev/null +++ b/test/fixedbugs/issue16369.go @@ -0,0 +1,13 @@ +// errorcheck + +// Copyright 2016 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 p + +type T interface { + M(interface { + T + }) // ERROR "cannot export unnamed recursive interface" +} -- cgit v1.2.3-54-g00ecf