From: fanzha02 <fannie.zhang@arm.com>
Date: Thu, 30 Dec 2021 03:09:42 +0000 (+0800)
Subject: src/runtime: mark asanread and asanwrite functions as NOSPLIT
X-Git-Tag: go1.18beta2~168
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=2c58bb2e428c1f587dc30817bc211570f6fd4793;p=gostls13.git

src/runtime: mark asanread and asanwrite functions as NOSPLIT

The asan runtime functions may run on stacks that cannot grow, and
they do not have large local variables, so it is safe to mark them
as NOSPLIT.

Add test case.

Fixes #50391

Change-Id: Iadcbf1ae0c837d9b64da5be208c7f424e6ba11de
Reviewed-on: https://go-review.googlesource.com/c/go/+/374398
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
Trust: Fannie Zhang <Fannie.Zhang@arm.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---

diff --git a/misc/cgo/testsanitizers/asan_test.go b/misc/cgo/testsanitizers/asan_test.go
index 27bd8a5b1f..1b70bce3d1 100644
--- a/misc/cgo/testsanitizers/asan_test.go
+++ b/misc/cgo/testsanitizers/asan_test.go
@@ -39,6 +39,7 @@ func TestASAN(t *testing.T) {
 		{src: "asan2_fail.go", memoryAccessError: "heap-buffer-overflow", errorLocation: "asan2_fail.go:31"},
 		{src: "asan3_fail.go", memoryAccessError: "use-after-poison", errorLocation: "asan3_fail.go:13"},
 		{src: "asan4_fail.go", memoryAccessError: "use-after-poison", errorLocation: "asan4_fail.go:13"},
+		{src: "asan5_fail.go", memoryAccessError: "use-after-poison", errorLocation: "asan5_fail.go:18"},
 		{src: "asan_useAfterReturn.go"},
 	}
 	for _, tc := range cases {
diff --git a/misc/cgo/testsanitizers/testdata/asan5_fail.go b/misc/cgo/testsanitizers/testdata/asan5_fail.go
new file mode 100644
index 0000000000..d6853eab73
--- /dev/null
+++ b/misc/cgo/testsanitizers/testdata/asan5_fail.go
@@ -0,0 +1,21 @@
+package main
+
+import (
+	"fmt"
+	"runtime"
+	"unsafe"
+)
+
+func main() {
+	p := new([1024 * 1000]int)
+	p[0] = 10
+	r := bar(&p[1024*1000-1])
+	fmt.Printf("r value is %d", r)
+}
+
+func bar(a *int) int {
+	p := unsafe.Add(unsafe.Pointer(a), 2*unsafe.Sizeof(int(1)))
+	runtime.ASanWrite(p, 8) // BOOM
+	*((*int)(p)) = 10
+	return *((*int)(p))
+}
diff --git a/src/runtime/asan.go b/src/runtime/asan.go
index affafd4d8d..26656cd975 100644
--- a/src/runtime/asan.go
+++ b/src/runtime/asan.go
@@ -26,12 +26,16 @@ func ASanWrite(addr unsafe.Pointer, len int) {
 // Private interface for the runtime.
 const asanenabled = true
 
+// Mark asan(read, write) as NOSPLIT, because they may run
+// on stacks that cannot grow. See issue #50391.
+//go:nosplit
 func asanread(addr unsafe.Pointer, sz uintptr) {
 	sp := getcallersp()
 	pc := getcallerpc()
 	doasanread(addr, sz, sp, pc)
 }
 
+//go:nosplit
 func asanwrite(addr unsafe.Pointer, sz uintptr) {
 	sp := getcallersp()
 	pc := getcallerpc()