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=-11.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 1D177C433ED for ; Wed, 5 May 2021 14:29:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC1A6613BE for ; Wed, 5 May 2021 14:29:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232262AbhEEOaJ (ORCPT ); Wed, 5 May 2021 10:30:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45898 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231792AbhEEOaC (ORCPT ); Wed, 5 May 2021 10:30:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620224944; 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: in-reply-to:in-reply-to:references:references; bh=RQQG2ihJBlOzrcPULXDL8J2wsb5zgRIJOBGF70oizsY=; b=IhbVqoV/llvi2VaJYyNXtI8JtYfSxbGwYhnEY33z5VSN49Hx2dEXc1HtLcYmie7XOGGh8i yk1ZjL0QcdMsFI6uQkg9XgSOd1DqNPtpLtczVwVnqlnZLn4eJmHAMb+dxP0RtKzePnNVKO ePIelb+iswl8No9hQmgxQ4/QX8T/cZM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-485-bDlbi2vgOduh4xNKWqGRbA-1; Wed, 05 May 2021 10:29:00 -0400 X-MC-Unique: bDlbi2vgOduh4xNKWqGRbA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AD998107ACE3; Wed, 5 May 2021 14:28:58 +0000 (UTC) Received: from T590 (ovpn-12-80.pek2.redhat.com [10.72.12.80]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1658360BF1; Wed, 5 May 2021 14:28:50 +0000 (UTC) Date: Wed, 5 May 2021 22:28:46 +0800 From: Ming Lei To: John Garry Cc: Jens Axboe , linux-block@vger.kernel.org, Bart Van Assche , Khazhy Kumykov , Shin'ichiro Kawasaki , Hannes Reinecke , David Jeffery Subject: Re: [PATCH V4 0/4] blk-mq: fix request UAF related with iterating over tagset requests Message-ID: References: <20210429023458.3044317-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, May 05, 2021 at 12:19:21PM +0100, John Garry wrote: > On 04/05/2021 12:43, Ming Lei wrote: > > > */ > > > - if (rq && rq->q == hctx->queue && rq->mq_hctx == hctx) > > > - return iter_data->fn(hctx, rq, iter_data->data, reserved); > > > + if (rq) { > > > + mdelay(50); > > > + if (rq->q == hctx->queue && rq->mq_hctx == hctx) > > > + return iter_data->fn(hctx, rq, iter_data->data, reserved); > > > + } > > > return true; > > > } > > hammmm, forget to cover bt_iter(), please test the following delta > > patch: > > > > > > diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c > > index a3be267212b9..27815114ee3f 100644 > > --- a/block/blk-mq-tag.c > > +++ b/block/blk-mq-tag.c > > @@ -206,18 +206,28 @@ static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) > > struct blk_mq_tags *tags = hctx->tags; > > bool reserved = iter_data->reserved; > > struct request *rq; > > + unsigned long flags; > > + bool ret = true; > > if (!reserved) > > bitnr += tags->nr_reserved_tags; > > - rq = tags->rqs[bitnr]; > > + spin_lock_irqsave(&tags->lock, flags); > > + rq = tags->rqs[bitnr]; > > /* > > * We can hit rq == NULL here, because the tagging functions > > * test and set the bit before assigning ->rqs[]. > > */ > > - if (rq && rq->q == hctx->queue && rq->mq_hctx == hctx) > > - return iter_data->fn(hctx, rq, iter_data->data, reserved); > > - return true; > > + if (!rq || !refcount_inc_not_zero(&rq->ref)) { > > + spin_unlock_irqrestore(&tags->lock, flags); > > + return true; > > + } > > + spin_unlock_irqrestore(&tags->lock, flags); > > + > > + if (rq->q == hctx->queue && rq->mq_hctx == hctx) > > + ret = iter_data->fn(hctx, rq, iter_data->data, reserved); > > + blk_mq_put_rq_ref(rq); > > + return ret; > > } > > > This looks to work ok from my testing. OK, thanks for your test, and will add your tested-by in V4. Thanks, Ming