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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 63893C433FE for ; Mon, 17 Oct 2022 12:24:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230031AbiJQMYI (ORCPT ); Mon, 17 Oct 2022 08:24:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230110AbiJQMYD (ORCPT ); Mon, 17 Oct 2022 08:24:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 243141EC47 for ; Mon, 17 Oct 2022 05:23:57 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A33036111E for ; Mon, 17 Oct 2022 12:23:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72D76C433C1; Mon, 17 Oct 2022 12:23:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666009436; bh=8V48uvPxGKFSi7OzFbIVPe2DEkGqM7SFVUeaOyfbN3E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=uvLmd6eyRhVc1yDiqwXpr/XUYCNldnt2B9A/92GqZe7Ze0R+KgWEw6dnNMi4NiIaF BxW4xq9n3USmmHZ+AZxOsTokKjpYMIapljvutoiuCIuufSmnHZrh2rkQTrj3MMjJH4 oj3byZtSHBgheCOviq7KUqfL4NRFba4k29i2g0l93wvoyFlkAGFsKVqeDvf0Kti0hb ClNHb1s/0D6ax+gJTWpzaylm/ncqIfWi7GlIkzaIm3NkQNmHSsj+UYl+qoeCtkJtRk oW6CVlc0qmxI48gArUfgrfqFTi2YBcnwfpNsJWrvK3uadAERerZzYo25htTehhMS3U 5SuFDJuO1OPzQ== Message-ID: <39c430b1-f4f1-e0a7-1089-9db85d1163d9@kernel.org> Date: Mon, 17 Oct 2022 20:23:51 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.3.1 Subject: Re: [PATCH] fs: f2fs: fix kernel discard_thread NULL dereference Content-Language: en-US To: Hoi Pok Wu , jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, syzbot+035a381ea1afb63f098d@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com References: <20221017100437.618363-1-wuhoipok@gmail.com> From: Chao Yu In-Reply-To: <20221017100437.618363-1-wuhoipok@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/10/17 18:04, Hoi Pok Wu wrote: > Pointer discard_thread is pointing to nowhere, using IS_ERR prevents the > situation. IS_ERR also seen being used throughout the file. I guess below patch can fix this issue from root cause? https://lore.kernel.org/linux-f2fs-devel/20221013155628.434671-1-chao@kernel.org/T/#u Thanks, > > Link: https://syzkaller.appspot.com/bug?id=9499bc6574cea5940e48199c2fd0732d9b11e5e1 > Reported-by: syzbot+035a381ea1afb63f098d@syzkaller.appspotmail.com > Signed-off-by: Hoi Pok Wu > --- > fs/f2fs/segment.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index acf3d3fa4363..79978b7206b5 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -1634,7 +1634,8 @@ void f2fs_stop_discard_thread(struct f2fs_sb_info *sbi) > struct task_struct *discard_thread = dcc->f2fs_issue_discard; > > dcc->f2fs_issue_discard = NULL; > - kthread_stop(discard_thread); > + if (!IS_ERR(discard_thread)) > + kthread_stop(discard_thread); > } > } >