From patchwork Wed May 3 14:01:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13230193 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8D7B8C77B78 for ; Wed, 3 May 2023 14:02:08 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1puD3I-0002cF-1q; Wed, 03 May 2023 10:01:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1puD3G-0002at-Hk for qemu-devel@nongnu.org; Wed, 03 May 2023 10:01:50 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1puD3F-0003Xs-4d for qemu-devel@nongnu.org; Wed, 03 May 2023 10:01:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1683122508; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=6NhsBJr2pi062KXhnbLfmOoLQAj3luaAICcAXzD8gwg=; b=H/3TngdLfs7oFzZJd/iFlPoEPl9PKDlN7/hQwm4Xiob6gY1a/wuuOBu6958Eh4bFGDBbTA dqY8VJmdNdtfXRpGKkUJn3XMTW3TeltDLwyhmX6t6BiDHaBFgOjpx0S1H3y+8/4jyh8ceP 3uGc+l34LPJxgWWhRI5h/XA0f23nm8M= 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-323-T_Rpr7niNyeKGKUYHI4PmQ-1; Wed, 03 May 2023 10:01:45 -0400 X-MC-Unique: T_Rpr7niNyeKGKUYHI4PmQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 34A7B85D540; Wed, 3 May 2023 14:01:45 +0000 (UTC) Received: from merkur.str.redhat.com (dhcp-192-205.str.redhat.com [10.33.192.205]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7EAF51410F29; Wed, 3 May 2023 14:01:44 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, stefanha@redhat.com, qemu-devel@nongnu.org Subject: [PATCH] block: Fix use after free in blockdev_mark_auto_del() Date: Wed, 3 May 2023 16:01:42 +0200 Message-Id: <20230503140142.474404-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.161, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org job_cancel_locked() drops the job list lock temporarily and it may call aio_poll(). We must assume that the list has changed after this call. Also, with unlucky timing, it can end up freeing the job during job_completed_txn_abort_locked(), making the job pointer invalid, too. For both reasons, we can't just continue at block_job_next_locked(job). Instead, start at the head of the list again after job_cancel_locked() and skip those jobs that we already cancelled (or that are completing anyway). Signed-off-by: Kevin Wolf Reviewed-by: Stefan Hajnoczi --- blockdev.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/blockdev.c b/blockdev.c index d7b5c18f0a..2c1752a403 100644 --- a/blockdev.c +++ b/blockdev.c @@ -153,12 +153,22 @@ void blockdev_mark_auto_del(BlockBackend *blk) JOB_LOCK_GUARD(); - for (job = block_job_next_locked(NULL); job; - job = block_job_next_locked(job)) { - if (block_job_has_bdrv(job, blk_bs(blk))) { + do { + job = block_job_next_locked(NULL); + while (job && (job->job.cancelled || + job->job.deferred_to_main_loop || + !block_job_has_bdrv(job, blk_bs(blk)))) + { + job = block_job_next_locked(job); + } + if (job) { + /* + * This drops the job lock temporarily and polls, so we need to + * restart processing the list from the start after this. + */ job_cancel_locked(&job->job, false); } - } + } while (job); dinfo->auto_del = 1; }