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master
test/fixedbugs/issue29362b.go
53 строки
1 KB
Keith Randall
runtime: don't scan go'd function args past length of ptr bitmap
04 янв 2019, 02:37
04 янв 2019, 02:37
6886677
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// run // Copyright 2018 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. // Verify that we don't consider a Go'd function's // arguments as pointers when they aren't. package main import ( "unsafe" ) var badPtr uintptr var sink []byte func init() { // Allocate large enough to use largeAlloc. b := make([]byte, 1<<16-1) sink = b // force heap allocation // Any space between the object and the end of page is invalid to point to. badPtr = uintptr(unsafe.Pointer(&b[len(b)-1])) + 1 } var throttle = make(chan struct{}, 10) // There are 2 arg bitmaps for this function, each with 2 bits. // In the first, p and q are both live, so that bitmap is 11. // In the second, only p is live, so that bitmap is 10. // Bitmaps are byte aligned, so if the first bitmap is interpreted as // extending across the entire argument area, we incorrectly concatenate // the bitmaps and end up using 110000001. That bad bitmap causes a6 // to be considered a pointer. func noPointerArgs(p, q *byte, a0, a1, a2, a3, a4, a5, a6 uintptr) { sink = make([]byte, 4096) sinkptr = q <-throttle sinkptr = p } var sinkptr *byte func main() { const N = 1000 for i := 0; i < N; i++ { throttle <- struct{}{} go noPointerArgs(nil, nil, badPtr, badPtr, badPtr, badPtr, badPtr, badPtr, badPtr) sink = make([]byte, 4096) } }