From c1fc209c41c18806b7cef1cf114f1ca9b3731eb9 Mon Sep 17 00:00:00 2001 From: Keith Randall Date: Wed, 23 Apr 2025 14:15:51 -0700 Subject: [PATCH] runtime: use precise bounds of Go data/bss for race detector We only want to call into the race detector for Go global variables. By rounding up the region bounds, we can include some C globals. Even worse, we can include only *part* of a C global, leading to race{read,write}range calls which straddle the end of shadow memory. That causes the race detector to barf. Fix some off-by-one errors in the assembly comparisons. We want to skip calling the race detector when addr == racedataend. Fixes #73483 Change-Id: I436b0f588d6165b61f30cb7653016ba9b7cbf585 Reviewed-on: https://go-review.googlesource.com/c/go/+/667655 Reviewed-by: Keith Randall Auto-Submit: Keith Randall LUCI-TryBot-Result: Go LUCI Reviewed-by: Dmitry Vyukov --- src/runtime/race.go | 10 ++++++---- src/runtime/race_arm64.s | 2 +- src/runtime/race_ppc64le.s | 2 +- test/fixedbugs/issue73483.go | 20 ++++++++++++++++++++ 4 files changed, 28 insertions(+), 6 deletions(-) create mode 100644 test/fixedbugs/issue73483.go diff --git a/src/runtime/race.go b/src/runtime/race.go index 6b7bbe5245..fa781a3ccc 100644 --- a/src/runtime/race.go +++ b/src/runtime/race.go @@ -455,7 +455,6 @@ func raceinit() (gctx, pctx uintptr) { racecall(&__tsan_init, uintptr(unsafe.Pointer(&gctx)), uintptr(unsafe.Pointer(&pctx)), abi.FuncPCABI0(racecallbackthunk), 0) - // Round data segment to page boundaries, because it's used in mmap(). start := ^uintptr(0) end := uintptr(0) if start > firstmoduledata.noptrdata { @@ -482,10 +481,13 @@ func raceinit() (gctx, pctx uintptr) { if end < firstmoduledata.ebss { end = firstmoduledata.ebss } - size := alignUp(end-start, _PageSize) - racecall(&__tsan_map_shadow, start, size, 0, 0) + // Use exact bounds for boundary check in racecalladdr. See issue 73483. racedatastart = start - racedataend = start + size + racedataend = end + // Round data segment to page boundaries for race detector (TODO: still needed?) + start = alignDown(start, _PageSize) + end = alignUp(end, _PageSize) + racecall(&__tsan_map_shadow, start, end-start, 0, 0) return } diff --git a/src/runtime/race_arm64.s b/src/runtime/race_arm64.s index c42a6c1377..83dfdef2e5 100644 --- a/src/runtime/race_arm64.s +++ b/src/runtime/race_arm64.s @@ -163,7 +163,7 @@ data: BLT ret MOVD runtime·racedataend(SB), R10 CMP R10, R1 - BGT ret + BGE ret call: JMP racecall<>(SB) ret: diff --git a/src/runtime/race_ppc64le.s b/src/runtime/race_ppc64le.s index 43829479bd..d3cac03ff4 100644 --- a/src/runtime/race_ppc64le.s +++ b/src/runtime/race_ppc64le.s @@ -153,7 +153,7 @@ data: BLT ret MOVD runtime·racedataend(SB), R9 CMP R4, R9 - BGT ret + BGE ret call: // Careful!! racecall will save LR on its // stack, which is OK as long as racecalladdr diff --git a/test/fixedbugs/issue73483.go b/test/fixedbugs/issue73483.go new file mode 100644 index 0000000000..8cd0c3433a --- /dev/null +++ b/test/fixedbugs/issue73483.go @@ -0,0 +1,20 @@ +// run -race + +//go:build race && cgo + +// Copyright 2025 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 + +/* + int v[8192]; +*/ +import "C" + +var x [8192]C.int + +func main() { + copy(C.v[:], x[:]) +}