From patchwork Fri Sep 10 08:56:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Garzarella X-Patchwork-Id: 12484639 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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,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 5FD39C433EF for ; Fri, 10 Sep 2021 08:56:54 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id F347B60234 for ; Fri, 10 Sep 2021 08:56:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org F347B60234 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:57308 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mOcL7-0001j7-1M for qemu-devel@archiver.kernel.org; Fri, 10 Sep 2021 04:56:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48560) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mOcKN-0000ay-SH for qemu-devel@nongnu.org; Fri, 10 Sep 2021 04:56:07 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:25033) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mOcKM-0006iT-1P for qemu-devel@nongnu.org; Fri, 10 Sep 2021 04:56:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631264164; 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; bh=P3l1VGBadgcaykJ9DACAzL4G3TzETxqvYTCGkvfwrW0=; b=EbMpqRFMIPHAL6FU0MbYMIgoYcHftQ8o6CA5mMXPHUoO6PNZd3fMxn8oosgotl/khuJppd zh49jbndgUhux0MQcW4S08dfrad+QzF5pi2I3lylBrirwciMlUodDEqOlCtMRovW/nwYDv 3WRo2ZVNVQ7TIB5V/dU5c76yu/lUScI= 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-492-y3yHrDqPMke5-4T6sKzQKw-1; Fri, 10 Sep 2021 04:56:03 -0400 X-MC-Unique: y3yHrDqPMke5-4T6sKzQKw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D3891101AFC0; Fri, 10 Sep 2021 08:56:02 +0000 (UTC) Received: from steredhat.redhat.com (unknown [10.39.193.209]) by smtp.corp.redhat.com (Postfix) with ESMTP id 70C6F19C79; Fri, 10 Sep 2021 08:56:01 +0000 (UTC) From: Stefano Garzarella To: qemu-devel@nongnu.org Subject: [PATCH] block/mirror: fix NULL pointer dereference in mirror_wait_on_conflicts() Date: Fri, 10 Sep 2021 10:56:00 +0200 Message-Id: <20210910085600.137772-1-sgarzare@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=sgarzare@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.133.124; envelope-from=sgarzare@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.393, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Hanna Reitz , Vladimir Sementsov-Ogievskiy , John Snow , qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" In mirror_iteration() we call mirror_wait_on_conflicts() with `self` parameter set to NULL. Starting from commit d44dae1a7c we dereference `self` pointer in mirror_wait_on_conflicts() without checks if it is not NULL. Backtrace: Program terminated with signal SIGSEGV, Segmentation fault. #0 mirror_wait_on_conflicts (self=0x0, s=, offset=, bytes=) at ../block/mirror.c:172 172 self->waiting_for_op = op; [Current thread is 1 (Thread 0x7f0908931ec0 (LWP 380249))] (gdb) bt #0 mirror_wait_on_conflicts (self=0x0, s=, offset=, bytes=) at ../block/mirror.c:172 #1 0x00005610c5d9d631 in mirror_run (job=0x5610c76a2c00, errp=) at ../block/mirror.c:491 #2 0x00005610c5d58726 in job_co_entry (opaque=0x5610c76a2c00) at ../job.c:917 #3 0x00005610c5f046c6 in coroutine_trampoline (i0=, i1=) at ../util/coroutine-ucontext.c:173 #4 0x00007f0909975820 in ?? () at ../sysdeps/unix/sysv/linux/x86_64/__start_context.S:91 from /usr/lib64/libc.so.6 Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001404 Fixes: d44dae1a7c ("block/mirror: fix active mirror dead-lock in mirror_wait_on_conflicts") Signed-off-by: Stefano Garzarella --- I'm not familiar with this code so maybe we can fix the bug differently. Running iotests and the test in bugzilla, everything seems okay. Thanks, Stefano --- block/mirror.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index 98fc66eabf..6c834d6a7b 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -169,9 +169,16 @@ static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self, continue; } - self->waiting_for_op = op; + if (self) { + self->waiting_for_op = op; + } + qemu_co_queue_wait(&op->waiting_requests, NULL); - self->waiting_for_op = NULL; + + if (self) { + self->waiting_for_op = NULL; + } + break; } }