From: Andy Pan <panjf2000@gmail.com>
Date: Sun, 25 Sep 2022 05:14:24 +0000 (+0800)
Subject: syscall: check if to is nil to prevent panic from Sendto
X-Git-Tag: go1.20rc1~943
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=5036ed26bd241cb8eadf4d0f00de6b9d3449bf87;p=gostls13.git

syscall: check if to is nil to prevent panic from Sendto

Fixes #55845

Change-Id: If30263b7d34829c40e6606846115ec520f351f2c
Reviewed-on: https://go-review.googlesource.com/c/go/+/433504
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Andy Pan <panjf2000@gmail.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
---

diff --git a/src/syscall/syscall_unix.go b/src/syscall/syscall_unix.go
index 3133becd7c..c59d4fcf95 100644
--- a/src/syscall/syscall_unix.go
+++ b/src/syscall/syscall_unix.go
@@ -437,11 +437,17 @@ func sendtoInet6(fd int, p []byte, flags int, to *SockaddrInet6) (err error) {
 }
 
 func Sendto(fd int, p []byte, flags int, to Sockaddr) (err error) {
-	ptr, n, err := to.sockaddr()
-	if err != nil {
-		return err
+	var (
+		ptr   unsafe.Pointer
+		salen _Socklen
+	)
+	if to != nil {
+		ptr, salen, err = to.sockaddr()
+		if err != nil {
+			return err
+		}
 	}
-	return sendto(fd, p, flags, ptr, n)
+	return sendto(fd, p, flags, ptr, salen)
 }
 
 func SetsockoptByte(fd, level, opt int, value byte) (err error) {