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=-18.2 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_SANE_1 autolearn=ham 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 83523C4338F for ; Mon, 26 Jul 2021 21:30:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6641C60F6C for ; Mon, 26 Jul 2021 21:30:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231926AbhGZUuS (ORCPT ); Mon, 26 Jul 2021 16:50:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:42218 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229489AbhGZUuR (ORCPT ); Mon, 26 Jul 2021 16:50:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E5B8C60F6B; Mon, 26 Jul 2021 21:30:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627335045; bh=10sumWN6KbuT6Bm4qG/cts13R1eLADJ18/WfByzAeGs=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=Qnm4bnw50azM1D1dMwCqm5ptC3S/j1h5Z0cBjmlIcP5NPuh+X9gt4fF9/ABBZV6D+ 2nEaKThLrbUKediyIMqJxAn6iUblKyjXsZaVlP27lt0Yd1WDcY+AYHsbc+qKd1Fn9P HjT8TsxDJBw2WE4+f33fSnw66hvdPKEARchNVDuwYY51Tuwzh6xPceTNMSlj0lPwuK Tcxy+IGN1VoV1haxQF40g/uNJ5HWgG7rCHR9ZJKucSfkMx+PYEeLIISWffeLlikCOU iLjUZi2+DjiC7yH2c+JGyB+dGWAzcfMWrNOX8b/vPLNrEbzRDEnWiBEdVBL0WgtYTI iVss8A5X/hBBQ== Date: Mon, 26 Jul 2021 14:30:44 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-T480s To: asmadeus@codewreck.org cc: Harshvardhan Jha , Stefano Stabellini , ericvh@gmail.com, lucho@ionkov.net, davem@davemloft.net, kuba@kernel.org, v9fs-developer@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] 9p/xen: Fix end of loop tests for list_for_each_entry In-Reply-To: Message-ID: References: <20210725175103.56731-1-harshvardhan.jha@oracle.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 26 Jul 2021, asmadeus@codewreck.org wrote: > Harshvardhan Jha wrote on Sun, Jul 25, 2021 at 11:21:03PM +0530: > > The list_for_each_entry() iterator, "priv" in this code, can never be > > NULL so the warning would never be printed. > > hm? priv won't be NULL but priv->client won't be client, so it will > return -EINVAL alright in practice? > > This does fix an invalid read after the list head, so there's a real > bug, but the commit message needs fixing. Agreed > > Signed-off-by: Harshvardhan Jha > > --- > > From static analysis. Not tested. > > +Stefano in To - I also can't test xen right now :/ > This looks functional to me but if you have a bit of time to spare just > a mount test can't hurt. Yes, I did test it successfully. Aside from the commit messaged to be reworded: Reviewed-by: Stefano Stabellini Tested-by: Stefano Stabellini > > --- > > net/9p/trans_xen.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c > > index f4fea28e05da..3ec1a51a6944 100644 > > --- a/net/9p/trans_xen.c > > +++ b/net/9p/trans_xen.c > > @@ -138,7 +138,7 @@ static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size) > > > > static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) > > { > > - struct xen_9pfs_front_priv *priv = NULL; > > + struct xen_9pfs_front_priv *priv; > > RING_IDX cons, prod, masked_cons, masked_prod; > > unsigned long flags; > > u32 size = p9_req->tc.size; > > @@ -151,7 +151,7 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) > > break; > > } > > read_unlock(&xen_9pfs_lock); > > - if (!priv || priv->client != client) > > + if (list_entry_is_head(priv, &xen_9pfs_devs, list)) > > return -EINVAL; > > > > num = p9_req->tc.tag % priv->num_rings;