From nobody Fri Nov 29 02:50:21 2024 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D99376FDC; Wed, 25 Sep 2024 11:25:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727263538; cv=none; b=UlFQ4XcOiw6fuys48jkJezY55tc8lPkkM1IwbViaFTYUrbEQwCc7rKwKMXsPr8/YhUcNfbe57O2JZ5jeAvMGGqugaYMPOxESq0l/z1WZojm8AQj7epHsv7mpLgN7WX4puCdrXijeIMUiJutYlKRnytTUspweGGbyAx4srdO5kaQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727263538; c=relaxed/simple; bh=puhxPJH/amOnms7SLF2+4j5c1YRzIKGbh4esV2Il+tA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=keKLVVepb1YABLJkceXTb4xITWnlP0AWk5ltNxMI1lJDtj+Evx3v57yUaEW2tLK/oZFdqP/xqsMx2tEfj5em+ca8CH91v4yWnaUlPiLc1AnZuUp9WUmybr3NzrkOWNfW6psoWtAmIW8fyJuwZxRJqn9AdLS0RjoG8AqktPyvHkM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=N20vghRL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="N20vghRL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A03EC4CEC3; Wed, 25 Sep 2024 11:25:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727263538; bh=puhxPJH/amOnms7SLF2+4j5c1YRzIKGbh4esV2Il+tA=; h=From:To:Cc:Subject:Date:From; b=N20vghRLGx1HqbBtVbX4cqbCJy7T4LsHJRnSCzM4sSUTwar6lQrTlqEfTawObD/2g +tTqdDd9cbzS7hlHrlTj4rqhSMBzClpljzBbZLamZKUKRNp7ceh89/TzF4FkuaTXmD 4JAyDQWlRz80B4XBYhDYzI8NahPKNo0ONMdq+NOa9lbA+qZObOKKFTsKsfkipCQPPL 5wHe2ESjcxLHraE0pl/rW6EOXTR78u2bP0YmAdMlGgKDsIBOHK0bNqxAIgZYCPjN0f ZwMPoXk6xolDbWUY3eZERc7ngsPoHZ8aZkh1HsIYcZcGJ19/4pcVYcI3Ji6YNTBscQ QjIBAyKiIbaaw== From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: Marco Bonelli , Masahiro Yamada , linux-kernel@vger.kernel.org Subject: [PATCH] kconfig: fix infinite loop in sym_calc_choice() Date: Wed, 25 Sep 2024 20:25:31 +0900 Message-ID: <20240925112533.184957-1-masahiroy@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Since commit f79dc03fe68c ("kconfig: refactor choice value calculation"), Kconfig for ARCH=3Dpowerpc may result in an infinite loop. This occurs because there are two entries for POWERPC64_CPU in a choice block. If the same symbol appears twice in a choice block, the ->choice_link node is added twice to ->choice_members, resulting a corrupted linked list. A simple test case is: choice prompt "choice" config X bool "X" config A bool "A prompt 1" config A bool "A prompt 2" endchoice Running 'make defconfig' results in an infinite loop. One solution is to replace the current two entries: config POWERPC64_CPU bool "Generic (POWER5 and PowerPC 970 and above)" depends on PPC_BOOK3S_64 && !CPU_LITTLE_ENDIAN select PPC_64S_HASH_MMU config POWERPC64_CPU bool "Generic (POWER8 and above)" depends on PPC_BOOK3S_64 && CPU_LITTLE_ENDIAN select ARCH_HAS_FAST_MULTIPLIER select PPC_64S_HASH_MMU select PPC_HAS_LBARX_LHARX with the following single entry: config POWERPC64_CPU bool "Generic 64 bit powerpc" depends on PPC_BOOK3S_64 select ARCH_HAS_FAST_MULTIPLIER if CPU_LITTLE_ENDIAN select PPC_64S_HASH_MMU select PPC_HAS_LBARX_LHARX if CPU_LITTLE_ENDIAN In my opinion, the latter looks cleaner, but PowerPC maintainers may prefer to display different prompts depending on CPU_LITTLE_ENDIAN. For now, this commit fixes the issue in Kconfig, restoring the original behavior. I will reconsider whether such a use case is worth supporting. Fixes: f79dc03fe68c ("kconfig: refactor choice value calculation") Reported-by: Marco Bonelli Closes: https://lore.kernel.org/all/1763151587.3581913.1727224126288@privat= eemail.com/ Signed-off-by: Masahiro Yamada --- scripts/kconfig/parser.y | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/scripts/kconfig/parser.y b/scripts/kconfig/parser.y index 1ad60f9e164e..bc43fb67c7c4 100644 --- a/scripts/kconfig/parser.y +++ b/scripts/kconfig/parser.y @@ -159,8 +159,14 @@ config_stmt: config_entry_start config_option_list yynerrs++; } =20 - list_add_tail(¤t_entry->sym->choice_link, - ¤t_choice->choice_members); + /* + * If the same symbol appears twice in a choice block, the list + * node would be added twice, leading to a broken linked list. + * list_empty() ensures that this symbol has not yet added. + */ + if (list_empty(¤t_entry->sym->choice_link)) + list_add_tail(¤t_entry->sym->choice_link, + ¤t_choice->choice_members); } =20 printd(DEBUG_PARSE, "%s:%d:endconfig\n", cur_filename, cur_lineno); --=20 2.43.0