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e496e612b7
cgocall could previously invoke the race detector on an M whose P had been retaken. The race detector would attempt to use the P-local state from this stale P, racing with the thread that was actually wired to that P. The result was memory corruption of ThreadSanitizer's internal data structures that presented as hard-to-understand assertion failures and segfaults. Reorder cgocall so that it always acquires a P before invoking the race detector, and add a test that stresses the interaction between cgo and the race detector to protect against future bugs of this kind. Fixes #27660. Change-Id: Ide93f96a23490314d6647547140e0a412a97f0d4 Reviewed-on: https://go-review.googlesource.com/c/148717 Run-TryBot: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
55 lines
1.5 KiB
Go
55 lines
1.5 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Stress the interaction between the race detector and cgo in an
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// attempt to reproduce the memory corruption described in #27660.
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// The bug was very timing sensitive; at the time of writing this
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// test would only trigger the bug about once out of every five runs.
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package cgotest
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// #include <unistd.h>
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import "C"
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import (
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"context"
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"math/rand"
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"runtime"
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"sync"
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"testing"
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"time"
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)
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func test27660(t *testing.T) {
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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ints := make([]int, 100)
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locks := make([]sync.Mutex, 100)
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// Slowly create threads so that ThreadSanitizer is forced to
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// frequently resize its SyncClocks.
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for i := 0; i < 100; i++ {
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go func() {
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for ctx.Err() == nil {
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// Sleep in C for long enough that it is likely that the runtime
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// will retake this goroutine's currently wired P.
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C.usleep(1000 /* 1ms */)
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runtime.Gosched() // avoid starvation (see #28701)
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}
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}()
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go func() {
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// Trigger lots of synchronization and memory reads/writes to
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// increase the likelihood that the race described in #27660
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// results in corruption of ThreadSanitizer's internal state
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// and thus an assertion failure or segfault.
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for ctx.Err() == nil {
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j := rand.Intn(100)
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locks[j].Lock()
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ints[j]++
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locks[j].Unlock()
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}
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}()
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time.Sleep(time.Millisecond)
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}
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}
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