From nobody Thu May 2 04:43:09 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1631264217531704.401540155742; Fri, 10 Sep 2021 01:56:57 -0700 (PDT) Received: from localhost ([::1]:57308 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mOcLA-0001j7-BP for importer@patchew.org; Fri, 10 Sep 2021 04:56:56 -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 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 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) 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= X-MC-Unique: y3yHrDqPMke5-4T6sKzQKw-1 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 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; 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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1631264219263100001 Content-Type: text/plain; charset="utf-8" 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=3D0x0, s=3D, offset=3D<= optimized out>, bytes=3D) at ../block/mirror.c:172 172 self->waiting_for_op =3D op; [Current thread is 1 (Thread 0x7f0908931ec0 (LWP 380249))] (gdb) bt #0 mirror_wait_on_conflicts (self=3D0x0, s=3D, offset=3D<= optimized out>, bytes=3D) at ../block/mirror.c:172 #1 0x00005610c5d9d631 in mirror_run (job=3D0x5610c76a2c00, errp=3D) at ../block/mirror.c:491 #2 0x00005610c5d58726 in job_co_entry (opaque=3D0x5610c76a2c00) at ../jo= b.c:917 #3 0x00005610c5f046c6 in coroutine_trampoline (i0=3D, i1= =3D) at ../util/coroutine-ucontext.c:173 #4 0x00007f0909975820 in ?? () at ../sysdeps/unix/sysv/linux/x86_64/__st= art_context.S:91 from /usr/lib64/libc.so.6 Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=3D2001404 Fixes: d44dae1a7c ("block/mirror: fix active mirror dead-lock in mirror_wai= t_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(Mirr= orOp *self, continue; } =20 - self->waiting_for_op =3D op; + if (self) { + self->waiting_for_op =3D op; + } + qemu_co_queue_wait(&op->waiting_requests, NULL); - self->waiting_for_op =3D NULL; + + if (self) { + self->waiting_for_op =3D NULL; + } + break; } } --=20 2.31.1