From mboxrd@z Thu Jan 1 00:00:00 1970 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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 26B21C433B4 for ; Wed, 5 May 2021 17:21:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EB941608FE for ; Wed, 5 May 2021 17:21:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236610AbhEERWf (ORCPT ); Wed, 5 May 2021 13:22:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:46988 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237147AbhEEQ6Y (ORCPT ); Wed, 5 May 2021 12:58:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 46B88619B0; Wed, 5 May 2021 16:39:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620232778; bh=HNvOkNfzFgERXYRr3FBPoHd92Jf0xb9PgL8U1hhuMh0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Sq0DNMlhxei5OLCWGIc9+tWb3rbETTPHBh72QYyPnOmw0T5b+Iy2w28SXIbG6hxgp wjhesgdZdTsilDbwhF3cZRnKbczqV83dCa/RmIIe2oWxXXJFyEa/kULlkua3HLJg1D uZgTxTvs9ttKFLyrHlJRX2VgrqZAL4qLpWK2BhtMMMOoO0ArVFf8ZWCX2nNwR0MXXM 2M+G9ztb/jxzOqxnmZXRT/JrMxduzmz7aS3q3N4sMFx/j1vpR03+11vPB0zNIXOK3o WF2mUHfAV1QqTG5bGiy3pgEV3AqoePglvPK9DWVhM5K/nq3nSrFxwsEeNdG7LWLhRK 6EXC26t03QTxA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Mihai Moldovan , Masahiro Yamada , Sasha Levin , linux-kbuild@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 28/46] kconfig: nconf: stop endless search loops Date: Wed, 5 May 2021 12:38:38 -0400 Message-Id: <20210505163856.3463279-28-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210505163856.3463279-1-sashal@kernel.org> References: <20210505163856.3463279-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@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 b7c1ef757178..331b2cc917ec 100644 --- a/scripts/kconfig/nconf.c +++ b/scripts/kconfig/nconf.c @@ -503,8 +503,8 @@ 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) != NULL) -- 2.30.2