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 0523FC433EF for ; Mon, 21 Mar 2022 09:38:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345930AbiCUJjh (ORCPT ); Mon, 21 Mar 2022 05:39:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233668AbiCUJjb (ORCPT ); Mon, 21 Mar 2022 05:39:31 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8BDA4DF4 for ; Mon, 21 Mar 2022 02:38:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1647855482; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CKsx9lB6p9WZgwNtKRiFWqPlet0kE4LtzkeugjgOYxw=; b=g8tFGSwsSAAPj0jchcr5axtMYkZYVoXwoFu2llviMMuKHEFp0jlnL6DOt/ViPYOn/ZmprV bk6/K04/6y4c2a5K8LP7T8ADhwAaRFfUmAC4BHBFiKE9CVEvb//Wgfme7rwICBqdDJlGR8 /lzAjCtDb2DDGMvNT0VXBYLA2ygnrTc= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-322-jCMNr4XVNeSNL75jysd6Mg-1; Mon, 21 Mar 2022 05:37:58 -0400 X-MC-Unique: jCMNr4XVNeSNL75jysd6Mg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7D0411044562; Mon, 21 Mar 2022 09:37:58 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id AFA01400E11D; Mon, 21 Mar 2022 09:37:57 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <1745593.TLkxdtWsSY@leap> References: <1745593.TLkxdtWsSY@leap> <1821968.CQOukoFCf9@leap> <000000000000b1807c05daad8f98@google.com> <977073.1647852411@warthog.procyon.org.uk> To: "Fabio M. De Francesco" Cc: dhowells@redhat.com, christophe.jaillet@wanadoo.fr, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] KASAN: null-ptr-deref Read in __free_pages MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <985900.1647855477.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Mon, 21 Mar 2022 09:37:57 +0000 Message-ID: <985901.1647855477@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Fabio M. De Francesco wrote: > I cannot have any objection, it's up to you to decide :) Of course you can object. That's kind of the point of a review;-) How about the attached instead, then? David --- --- a/kernel/watch_queue.c +++ b/kernel/watch_queue.c @@ -271,9 +271,8 @@ long watch_queue_set_size(struct pipe_inode_info *pipe= , unsigned int nr_notes) return 0; = error_p: - for (i =3D 0; i < nr_pages; i++) - if (pages[i]) - __free_page(pages[i]); + while (--i >=3D 0) + __free_page(pages[i]); kfree(pages); error: (void) account_pipe_buffers(pipe->user, nr_pages, pipe->nr_accounted);