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mirror of https://github.com/golang/go synced 2024-11-11 19:21:37 -07:00

cmd/link: don't reset variable size when handling -X flag

The linker's -X flag allows setting/changing a string variable's
content at link time. Currently it resets its size then write a
new string header pointing to the new content. This mostly works.
But under ASAN build the string variable can have larger size
than the usual 2 words, due to the red zone. Resetting the size
can cause the variable to "overlap" (in ASAN's view) with other
variables. Don't reset the size.

Fixes #56175.

Change-Id: Ib364208201a7a2fd7f44f9b1797834198736a405
Reviewed-on: https://go-review.googlesource.com/c/go/+/442635
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Cherry Mui 2022-10-12 16:24:34 -04:00
parent 36ca37f3a0
commit 9fe17a0340
4 changed files with 88 additions and 4 deletions

View File

@ -5,6 +5,7 @@
package sanitizers_test
import (
"fmt"
"strings"
"testing"
)
@ -97,3 +98,44 @@ func TestASAN(t *testing.T) {
})
}
}
func TestASANLinkerX(t *testing.T) {
// Test ASAN with linker's -X flag (see issue 56175).
goos, err := goEnv("GOOS")
if err != nil {
t.Fatal(err)
}
goarch, err := goEnv("GOARCH")
if err != nil {
t.Fatal(err)
}
// The asan tests require support for the -asan option.
if !aSanSupported(goos, goarch) {
t.Skipf("skipping on %s/%s; -asan option is not supported.", goos, goarch)
}
if !compilerRequiredAsanVersion(goos, goarch) {
t.Skipf("skipping on %s/%s: too old version of compiler", goos, goarch)
}
t.Parallel()
requireOvercommit(t)
config := configure("address")
config.skipIfCSanitizerBroken(t)
dir := newTempDir(t)
defer dir.RemoveAll(t)
var ldflags string
for i := 1; i <= 10; i++ {
ldflags += fmt.Sprintf("-X=main.S%d=%d -X=misc/cgo/testsanitizers/testdata/asan_linkerx/p.S%d=%d ", i, i, i, i)
}
// build the binary
outPath := dir.Join("main.exe")
cmd := config.goCmd("build", "-ldflags="+ldflags, "-o", outPath)
cmd.Dir = srcPath("asan_linkerx")
mustRun(t, cmd)
// run the binary
mustRun(t, hangProneCmd(outPath))
}

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@ -0,0 +1,28 @@
package main
import "misc/cgo/testsanitizers/testdata/asan_linkerx/p"
func pstring(s *string) {
println(*s)
}
func main() {
all := []*string{
&S1, &S2, &S3, &S4, &S5, &S6, &S7, &S8, &S9, &S10,
&p.S1, &p.S2, &p.S3, &p.S4, &p.S5, &p.S6, &p.S7, &p.S8, &p.S9, &p.S10,
}
for _, ps := range all {
pstring(ps)
}
}
var S1 string
var S2 string
var S3 string
var S4 string
var S5 string
var S6 string
var S7 string
var S8 string
var S9 string
var S10 string

View File

@ -0,0 +1,12 @@
package p
var S1 string
var S2 string
var S3 string
var S4 string
var S5 string
var S6 string
var S7 string
var S8 string
var S9 string
var S10 string

View File

@ -1127,12 +1127,14 @@ func addstrdata(arch *sys.Arch, l *loader.Loader, name, value string) {
sbld.Addstring(value)
sbld.SetType(sym.SRODATA)
bld.SetSize(0)
bld.SetData(make([]byte, 0, arch.PtrSize*2))
// Don't reset the variable's size. String variable usually has size of
// 2*PtrSize, but in ASAN build it can be larger due to red zone.
// (See issue 56175.)
bld.SetData(make([]byte, arch.PtrSize*2))
bld.SetReadOnly(false)
bld.ResetRelocs()
bld.AddAddrPlus(arch, sbld.Sym(), 0)
bld.AddUint(arch, uint64(len(value)))
bld.SetAddrPlus(arch, 0, sbld.Sym(), 0)
bld.SetUint(arch, int64(arch.PtrSize), uint64(len(value)))
}
func (ctxt *Link) dostrdata() {