From: Ian Lance Taylor <iant@golang.org>
Date: Tue, 18 Apr 2023 21:48:36 +0000 (-0700)
Subject: net: check for NUL bytes in strings passed to C functions
X-Git-Tag: go1.21rc1~852
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=7e66a8ad400792bcf8049313a3142496ce5fd9a9;p=gostls13.git

net: check for NUL bytes in strings passed to C functions

Use syscall.BytePtrFromString and syscall.ByteSliceFromString.

Change-Id: I9409ecd93aaca82390bf3f34be56ec354148a241
Reviewed-on: https://go-review.googlesource.com/c/go/+/486015
Run-TryBot: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
---

diff --git a/src/net/cgo_unix.go b/src/net/cgo_unix.go
index c5281ad3a5..de6a64b23b 100644
--- a/src/net/cgo_unix.go
+++ b/src/net/cgo_unix.go
@@ -94,8 +94,10 @@ func cgoLookupPort(ctx context.Context, network, service string) (port int, err
 }
 
 func cgoLookupServicePort(hints *_C_struct_addrinfo, network, service string) (port int, err error) {
-	cservice := make([]byte, len(service)+1)
-	copy(cservice, service)
+	cservice, err := syscall.ByteSliceFromString(service)
+	if err != nil {
+		return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}
+	}
 	// Lowercase the C service name.
 	for i, b := range cservice[:len(service)] {
 		cservice[i] = lowerASCII(b)
@@ -147,10 +149,12 @@ func cgoLookupHostIP(network, name string) (addrs []IPAddr, err error) {
 		*_C_ai_family(&hints) = _C_AF_INET6
 	}
 
-	h := make([]byte, len(name)+1)
-	copy(h, name)
+	h, err := syscall.BytePtrFromString(name)
+	if err != nil {
+		return nil, &DNSError{Err: err.Error(), Name: name}
+	}
 	var res *_C_struct_addrinfo
-	gerrno, err := _C_getaddrinfo((*_C_char)(unsafe.Pointer(&h[0])), nil, &hints, &res)
+	gerrno, err := _C_getaddrinfo((*_C_char)(unsafe.Pointer(h)), nil, &hints, &res)
 	if gerrno != 0 {
 		isErrorNoSuchHost := false
 		isTemporary := false
@@ -325,12 +329,14 @@ func cgoResSearch(hostname string, rtype, class int) ([]dnsmessage.Resource, err
 	buf := (*_C_uchar)(_C_malloc(uintptr(bufSize)))
 	defer _C_free(unsafe.Pointer(buf))
 
-	s := _C_CString(hostname)
-	defer _C_FreeCString(s)
+	s, err := syscall.BytePtrFromString(hostname)
+	if err != nil {
+		return nil, err
+	}
 
 	var size int
 	for {
-		size, _ = _C_res_nsearch(state, s, class, rtype, buf, bufSize)
+		size, _ = _C_res_nsearch(state, (*_C_char)(unsafe.Pointer(s)), class, rtype, buf, bufSize)
 		if size <= 0 || size > 0xffff {
 			return nil, errors.New("res_nsearch failure")
 		}
diff --git a/src/net/cgo_unix_cgo.go b/src/net/cgo_unix_cgo.go
index c0aa373a9b..7520c5d95c 100644
--- a/src/net/cgo_unix_cgo.go
+++ b/src/net/cgo_unix_cgo.go
@@ -56,7 +56,6 @@ type (
 )
 
 func _C_GoString(p *_C_char) string      { return C.GoString(p) }
-func _C_CString(s string) *_C_char       { return C.CString(s) }
 func _C_FreeCString(p *_C_char)          { C.free(unsafe.Pointer(p)) }
 func _C_malloc(n uintptr) unsafe.Pointer { return C.malloc(C.size_t(n)) }
 func _C_free(p unsafe.Pointer)           { C.free(p) }
diff --git a/src/net/cgo_unix_syscall.go b/src/net/cgo_unix_syscall.go
index cbdeb47714..332ca6bc2f 100644
--- a/src/net/cgo_unix_syscall.go
+++ b/src/net/cgo_unix_syscall.go
@@ -43,12 +43,6 @@ func _C_GoString(p *_C_char) string {
 	return unix.GoString(p)
 }
 
-func _C_CString(s string) *_C_char {
-	p := make([]byte, len(s)+1)
-	copy(p, s)
-	return &p[0]
-}
-
 func _C_FreeCString(p *_C_char) { _C_free(unsafe.Pointer(p)) }
 func _C_free(p unsafe.Pointer)  { runtime.KeepAlive(p) }