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syscall: avoid memory corruption in mksyscall_windows.go with *bool parameters

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Windows type PBOOL is a pointer to a 4 byte value, where 0 means false
and not-0 means true. That means we should use uint32 here, not bool,
since Go bools can be 1 byte. Since a *bool is never a "real" valid
Windows type, converting on both in and out is probably sufficient,
since *bool shouldn't ever be used as something with significance for
its particular address.

Updates: #34364
Change-Id: I4c1b91cd9a39d91e23dae6f894b9a49f7fba2c0a
Reviewed-on: https://go-review.googlesource.com/c/go/+/196122
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
This commit is contained in:
Jason A. Donenfeld 2019-09-18 00:10:07 -06:00
parent fa42157d98
commit 62fb079e2b
1 changed files with 30 additions and 1 deletions
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31
src/syscall/mksyscall_windows.go
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@ -117,6 +117,18 @@ func (p *Param) BoolTmpVarCode() string {
return fmt.Sprintf(code, tmp, p.Name, tmp, tmp)
}
// BoolPointerTmpVarCode returns source code for bool temp variable.
func (p *Param) BoolPointerTmpVarCode() string {
const code = `var %s uint32
if *%s {
%s = 1
} else {
%s = 0
}`
tmp := p.tmpVar()
return fmt.Sprintf(code, tmp, p.Name, tmp, tmp)
}
// SliceTmpVarCode returns source code for slice temp variable.
func (p *Param) SliceTmpVarCode() string {
const code = `var %s *%s
@ -152,6 +164,8 @@ func (p *Param) TmpVarCode() string {
switch {
case p.Type == "bool":
return p.BoolTmpVarCode()
case p.Type == "*bool":
return p.BoolPointerTmpVarCode()
case strings.HasPrefix(p.Type, "[]"):
return p.SliceTmpVarCode()
default:
@ -159,6 +173,16 @@ func (p *Param) TmpVarCode() string {
}
}
// TmpVarReadbackCode returns source code for reading back the temp variable into the original variable.
func (p *Param) TmpVarReadbackCode() string {
switch {
case p.Type == "*bool":
return fmt.Sprintf("*%s = %s != 0", p.Name, p.tmpVar())
default:
return ""
}
}
// TmpVarHelperCode returns source code for helper's temp variable.
func (p *Param) TmpVarHelperCode() string {
if p.Type != "string" {
@ -174,6 +198,8 @@ func (p *Param) SyscallArgList() []string {
t := p.HelperType()
var s string
switch {
case t == "*bool":
s = fmt.Sprintf("unsafe.Pointer(&%s)", p.tmpVar())
case t[0] == '*':
s = fmt.Sprintf("unsafe.Pointer(%s)", p.Name)
case t == "bool":
@ -876,7 +902,7 @@ func {{.Name}}({{.ParamList}}) {{template "results" .}}{
{{define "funcbody"}}
func {{.HelperName}}({{.HelperParamList}}) {{template "results" .}}{
{{template "tmpvars" .}} {{template "syscall" .}}
{{template "tmpvars" .}} {{template "syscall" .}} {{template "tmpvarsreadback" .}}
{{template "seterror" .}}{{template "printtrace" .}} return
}
{{end}}
@ -891,6 +917,9 @@ func {{.HelperName}}({{.HelperParamList}}) {{template "results" .}}{
{{define "syscall"}}{{.Rets.SetReturnValuesCode}}{{.Syscall}}(proc{{.DLLFuncName}}.Addr(), {{.ParamCount}}, {{.SyscallParamList}}){{end}}
{{define "tmpvarsreadback"}}{{range .Params}}{{if .TmpVarReadbackCode}}
{{.TmpVarReadbackCode}}{{end}}{{end}}{{end}}
{{define "seterror"}}{{if .Rets.SetErrorCode}} {{.Rets.SetErrorCode}}
{{end}}{{end}}