From patchwork Thu May 20 09:22:54 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 444091 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AC414C433ED for ; Thu, 20 May 2021 11:04:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9552C61261 for ; Thu, 20 May 2021 11:04:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239211AbhETLFn (ORCPT ); Thu, 20 May 2021 07:05:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:38388 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239559AbhETLDe (ORCPT ); Thu, 20 May 2021 07:03:34 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id AEAC561D17; Thu, 20 May 2021 10:04:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621505071; bh=fTf4qo64soCDRDnKGHNUSCNtTuVdhpbH+CBMMyRAsiw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Cb1zt5s8ugoyKBFzoxRDjFC+FLKExWUTo6TBwxhN6q3pTL/NPSfeXVuAS9F0s3W1n Hcnxpvoz5YEhowqkBoLpFEkU2q/GTe1iOvIT8LA/oSTvcMjgTv4ynr8BmOrKjgExD3 KB+HD78qgdWGe/CtRYNoFyDE5Atr1eQHBS4jO8SI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mihai Moldovan , Masahiro Yamada , Sasha Levin Subject: [PATCH 4.9 182/240] kconfig: nconf: stop endless search loops Date: Thu, 20 May 2021 11:22:54 +0200 Message-Id: <20210520092114.771204915@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092108.587553970@linuxfoundation.org> References: <20210520092108.587553970@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mihai Moldovan [ Upstream commit 8c94b430b9f6213dec84e309bb480a71778c4213 ] If the user selects the very first entry in a page and performs a search-up operation, or selects the very last entry in a page and performs a search-down operation that will not succeed (e.g., via [/]asdfzzz[Up Arrow]), nconf will never terminate searching the page. The reason is that in this case, the starting point will be set to -1 or n, which is then translated into (n - 1) (i.e., the last entry of the page) or 0 (i.e., the first entry of the page) and finally the search begins. This continues to work fine until the index reaches 0 or (n - 1), at which point it will be decremented to -1 or incremented to n, but not checked against the starting point right away. Instead, it's wrapped around to the bottom or top again, after which the starting point check occurs... and naturally fails. My original implementation added another check for -1 before wrapping the running index variable around, but Masahiro Yamada pointed out that the actual issue is that the comparison point (starting point) exceeds bounds (i.e., the [0,n-1] interval) in the first place and that, instead, the starting point should be fixed. This has the welcome side-effect of also fixing the case where the starting point was n while searching down, which also lead to an infinite loop. OTOH, this code is now essentially all his work. Amazingly, nobody seems to have been hit by this for 11 years - or at the very least nobody bothered to debug and fix this. Signed-off-by: Mihai Moldovan Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin --- scripts/kconfig/nconf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/kconfig/nconf.c b/scripts/kconfig/nconf.c index f7049e288e93..c58a46904861 100644 --- a/scripts/kconfig/nconf.c +++ b/scripts/kconfig/nconf.c @@ -502,8 +502,8 @@ static int get_mext_match(const char *match_str, match_f flag) else if (flag == FIND_NEXT_MATCH_UP) --match_start; + match_start = (match_start + items_num) % items_num; index = match_start; - index = (index + items_num) % items_num; while (true) { char *str = k_menu_items[index].str; if (strcasestr(str, match_str) != 0)