kconfig: qconf: fix buffer overflow in debug links

[ Upstream commit 984ed20ece1c6c20789ece040cbff3eb1a388fa9 ]

If you enable "Option -> Show Debug Info" and click a link, the program
terminates with the following error:

    *** buffer overflow detected ***: terminated

The buffer overflow is caused by the following line:

    strcat(data, "$");

The buffer needs one more byte to accommodate the additional character.

Fixes: c4f7398bee ("kconfig: qconf: make debug links work again")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

scripts/kconfig/qconf.cc

@@ -1174,7 +1174,7 @@ void ConfigInfoView::clicked(const QUrl &url)
 {
 	QByteArray str = url.toEncoded();
 	const std::size_t count = str.size();
-	char *data = new char[count + 1];
+	char *data = new char[count + 2];  // '$' + '\0'
 	struct symbol **result;
 	struct menu *m = NULL;