From nobody Thu Apr 2 21:33:19 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8AA44ECAAD8 for ; Tue, 20 Sep 2022 15:59:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230216AbiITP7g (ORCPT ); Tue, 20 Sep 2022 11:59:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229764AbiITP7e (ORCPT ); Tue, 20 Sep 2022 11:59:34 -0400 Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 646AAD9A for ; Tue, 20 Sep 2022 08:59:32 -0700 (PDT) Received: from fsav119.sakura.ne.jp (fsav119.sakura.ne.jp [27.133.134.246]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 28KFxUm8092946; Wed, 21 Sep 2022 00:59:30 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav119.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav119.sakura.ne.jp); Wed, 21 Sep 2022 00:59:30 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav119.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 28KFxTq7092942 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Wed, 21 Sep 2022 00:59:30 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <4b37f037-3b10-b4e4-0644-73441c8fa0af@I-love.SAKURA.ne.jp> Date: Wed, 21 Sep 2022 00:59:27 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: [PATCH] fs/ntfs3: fix negative shift size in true_sectors_per_clst() Content-Language: en-US To: Konstantin Komarov , Andrew Morton , Namjae Jeon , Randy Dunlap References: <000000000000f8b5ef05dd25b963@google.com> Cc: syzbot , syzkaller-bugs@googlegroups.com, ntfs3@lists.linux.dev, LKML From: Tetsuo Handa In-Reply-To: <000000000000f8b5ef05dd25b963@google.com> Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" syzbot is reporting shift-out-of-bounds in true_sectors_per_clst() [1], for commit a3b774342fa752a5 ("fs/ntfs3: validate BOOT sectors_per_clusters") did not address that (0 - boot->sectors_per_clusters) < 0 because "u8" was chosen for type of boot->sectors_per_clusters because 0x80 needs to be positive in order to support 64K clusters. Use "s8" cast in order to make sure that (0 - (s8) boot->sectors_per_clusters) > 0. Link: https://syzkaller.appspot.com/bug?extid=3D1631f09646bc214d2e76 [1] Reported-by: syzbot Signed-off-by: Tetsuo Handa Tested-by: syzbot Fixes: a3b774342fa752a5 ("fs/ntfs3: validate BOOT sectors_per_clusters") diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c index 47012c9bf505..c7ffd21fb255 100644 --- a/fs/ntfs3/super.c +++ b/fs/ntfs3/super.c @@ -672,7 +672,7 @@ static u32 true_sectors_per_clst(const struct NTFS_BOOT= *boot) if (boot->sectors_per_clusters <=3D 0x80) return boot->sectors_per_clusters; if (boot->sectors_per_clusters >=3D 0xf4) /* limit shift to 2MB max */ - return 1U << (0 - boot->sectors_per_clusters); + return 1U << (0 - (s8) boot->sectors_per_clusters); return -EINVAL; } =20 --=20 2.18.4