[Network] Clear buffer before use.

Clean unix address buffer before use : more robust to bad user addresses missing trailing '\0',
 and prevents leaking data

Change-Id: I769b895327f97870886309a7054facd3c169fb7f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/10052
Reviewed-by: Adrien Destugues <[email protected]>
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: waddlesplash <[email protected]>

src/system/kernel/fs/socket.cpp

@@ -1099,6 +1099,7 @@ _user_sendto(int socket, const void *data, size_t length, int flags,
 
 	// copy address from userland
 	char address[MAX_SOCKET_ADDRESS_LENGTH];
+	memset(address, 0, MAX_SOCKET_ADDRESS_LENGTH);
 	if (userAddress != NULL) {
 		if (!IS_USER_ADDRESS(userAddress)
 			|| user_memcpy(address, userAddress, addressLength) != B_OK) {