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 7DD43C433EF for ; Mon, 14 Mar 2022 16:21:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242956AbiCNQWt (ORCPT ); Mon, 14 Mar 2022 12:22:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42040 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241710AbiCNQWp (ORCPT ); Mon, 14 Mar 2022 12:22:45 -0400 X-Greylist: delayed 392 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Mon, 14 Mar 2022 09:21:35 PDT Received: from sender4-of-o53.zoho.com (sender4-of-o53.zoho.com [136.143.188.53]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E915912A8A; Mon, 14 Mar 2022 09:21:34 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1647274883; cv=none; d=zohomail.com; s=zohoarc; b=mx2smIOGeo5ZjY9eOcc/bCGdqHmQUFR59CYhROKVr38Nz2LvTY2tlis1je8oqqd0yKOSOFIb3ccss3/zksRXDdKtAaOBo/XLyWQhKc0FI7PRZRUokt/E+aIaO2UpJtn/Jc9cWCIQjfKdC3m2Hs3FsvkoWmMtC9tuSTWyaiOAWL4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1647274883; h=Content-Type:Cc:Date:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:To; bh=exLHJy/o8u0v5+P+IbvaTX55kBTxm+CYnLzbshyskLQ=; b=iu4CwdmaeduL2TpUU/4fmKpgv8MJPLw2fzJSYQWr8mAlm8rCvRkNK66DdfEJZm91T/tobqETRn5aHHl1E93mkmUiQO5P4CQ0lVuaGa/HncCx5cAnlJrVARbX7KtCYMeLLfEiPaSCv97zYhpzKcFmzP6e6C5OdAkU2OZ1jFJo+tY= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=anirudhrb.com; spf=pass smtp.mailfrom=mail@anirudhrb.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1647274883; s=zoho; d=anirudhrb.com; i=mail@anirudhrb.com; h=Date:From:From:To:To:Cc:Cc:Subject:Subject:Message-ID:References:MIME-Version:Content-Type:In-Reply-To:Message-Id:Reply-To; bh=exLHJy/o8u0v5+P+IbvaTX55kBTxm+CYnLzbshyskLQ=; b=Kp+VnZ/0dusGp1M2OtccWhO6EKsLdjYBJFIL/BZh8jjtp9YNmAP+tnXWoYmaAUKN woajBDaQEecsACvn6Cbb+hH5wnmXnCikCQ98aMfwNtGyIiDPLHnWWG4AW0DC9hwsn8G aNrn8rPwsei/avKj+9tmYYtJK3Lht9mc2R/UUizw= Received: from anirudhrb.com (49.207.221.223 [49.207.221.223]) by mx.zohomail.com with SMTPS id 1647274843303560.9949108171496; Mon, 14 Mar 2022 09:20:43 -0700 (PDT) Date: Mon, 14 Mar 2022 21:50:36 +0530 From: Anirudh Rayabharam To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com, "Michael S. Tsirkin" , Sasha Levin , jasowang@redhat.com Subject: Re: [PATCH 5.16 017/121] vhost: fix hung thread due to erroneous iotlb entries Message-ID: References: <20220314112744.120491875@linuxfoundation.org> <20220314112744.608703877@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220314112744.608703877@linuxfoundation.org> X-ZohoMailClient: External Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 14, 2022 at 12:53:20PM +0100, Greg Kroah-Hartman wrote: > From: Anirudh Rayabharam > > [ Upstream commit e2ae38cf3d91837a493cb2093c87700ff3cbe667 ] This breaks batching of IOTLB messages. [1] fixes it but hasn't landed in Linus' tree yet. [1]: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/commit/?h=linux-next&id=95932ab2ea07b79cdb33121e2f40ccda9e6a73b5 - Anirudh. > > In vhost_iotlb_add_range_ctx(), range size can overflow to 0 when > start is 0 and last is ULONG_MAX. One instance where it can happen > is when userspace sends an IOTLB message with iova=size=uaddr=0 > (vhost_process_iotlb_msg). So, an entry with size = 0, start = 0, > last = ULONG_MAX ends up in the iotlb. Next time a packet is sent, > iotlb_access_ok() loops indefinitely due to that erroneous entry. > > Call Trace: > > iotlb_access_ok+0x21b/0x3e0 drivers/vhost/vhost.c:1340 > vq_meta_prefetch+0xbc/0x280 drivers/vhost/vhost.c:1366 > vhost_transport_do_send_pkt+0xe0/0xfd0 drivers/vhost/vsock.c:104 > vhost_worker+0x23d/0x3d0 drivers/vhost/vhost.c:372 > kthread+0x2e9/0x3a0 kernel/kthread.c:377 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 > > > Reported by syzbot at: > https://syzkaller.appspot.com/bug?extid=0abd373e2e50d704db87 > > To fix this, do two things: > > 1. Return -EINVAL in vhost_chr_write_iter() when userspace asks to map > a range with size 0. > 2. Fix vhost_iotlb_add_range_ctx() to handle the range [0, ULONG_MAX] > by splitting it into two entries. > > Fixes: 0bbe30668d89e ("vhost: factor out IOTLB") > Reported-by: syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com > Tested-by: syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com > Signed-off-by: Anirudh Rayabharam > Link: https://lore.kernel.org/r/20220305095525.5145-1-mail@anirudhrb.com > Signed-off-by: Michael S. Tsirkin > Signed-off-by: Sasha Levin > --- > drivers/vhost/iotlb.c | 11 +++++++++++ > drivers/vhost/vhost.c | 5 +++++ > 2 files changed, 16 insertions(+) > > diff --git a/drivers/vhost/iotlb.c b/drivers/vhost/iotlb.c > index 670d56c879e5..40b098320b2a 100644 > --- a/drivers/vhost/iotlb.c > +++ b/drivers/vhost/iotlb.c > @@ -57,6 +57,17 @@ int vhost_iotlb_add_range_ctx(struct vhost_iotlb *iotlb, > if (last < start) > return -EFAULT; > > + /* If the range being mapped is [0, ULONG_MAX], split it into two entries > + * otherwise its size would overflow u64. > + */ > + if (start == 0 && last == ULONG_MAX) { > + u64 mid = last / 2; > + > + vhost_iotlb_add_range_ctx(iotlb, start, mid, addr, perm, opaque); > + addr += mid + 1; > + start = mid + 1; > + } > + > if (iotlb->limit && > iotlb->nmaps == iotlb->limit && > iotlb->flags & VHOST_IOTLB_FLAG_RETIRE) { > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 59edb5a1ffe2..55475fd59fb7 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -1170,6 +1170,11 @@ ssize_t vhost_chr_write_iter(struct vhost_dev *dev, > goto done; > } > > + if (msg.size == 0) { > + ret = -EINVAL; > + goto done; > + } > + > if (dev->msg_handler) > ret = dev->msg_handler(dev, &msg); > else > -- > 2.34.1 > > >