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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46580 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ldX9c-0002Uf-Q0 for qemu-devel@archiver.kernel.org; Mon, 03 May 2021 07:54:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47162) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ldX8b-0001bT-RE for qemu-devel@nongnu.org; Mon, 03 May 2021 07:53:21 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:25154) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ldX8a-0002Rs-9p for qemu-devel@nongnu.org; Mon, 03 May 2021 07:53:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620042799; 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: in-reply-to:in-reply-to:references:references; bh=8kkAR5EGfAE090OPh/KsGJX+brYK4EqBaKBuN9HwdL8=; b=WS/MIIuhddebD/4yiZV79T/NEQBR+YrmcvIkKYbY+qSc4N2jP+KEHQcBQQMhCNbXeKGDCO dr1ggC8OkkfVFSmtQi9hkH0er/V92LyX5alUJ6yxSB0j3J+uSn0rLEuvyyz3P5e/sMxLvE bfyNZO1hstYfAW2UOg2tV3pYyiIZf4A= 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-475-_02GWk6eMmilFqAyiBd1Ng-1; Mon, 03 May 2021 07:53:16 -0400 X-MC-Unique: _02GWk6eMmilFqAyiBd1Ng-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 44DA5801106; Mon, 3 May 2021 11:53:15 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-114-107.ams2.redhat.com [10.36.114.107]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3492B10013C1; Mon, 3 May 2021 11:53:13 +0000 (UTC) Subject: Re: [PATCH 1/2] block: Fix Transaction leak in bdrv_root_attach_child() To: Vladimir Sementsov-Ogievskiy , Kevin Wolf , qemu-block@nongnu.org References: <20210503110555.24001-1-kwolf@redhat.com> <20210503110555.24001-2-kwolf@redhat.com> <9e23f679-84ac-9d1a-09dc-4894cd9d6979@redhat.com> From: Max Reitz Message-ID: Date: Mon, 3 May 2021 13:53:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.698, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 03.05.21 13:51, Vladimir Sementsov-Ogievskiy wrote: > 03.05.2021 14:49, Max Reitz wrote: >> On 03.05.21 13:05, Kevin Wolf wrote: >>> The error path needs to call tran_finalize(), too. >>> >>> Fixes: CID 1452773 >>> Fixes: 548a74c0dbc858edd1a7ee3045b5f2fe710bd8b1 >>> Signed-off-by: Kevin Wolf >>> --- >>>   block.c | 7 ++++--- >>>   1 file changed, 4 insertions(+), 3 deletions(-) >>> >>> diff --git a/block.c b/block.c >>> index 874c22c43e..5c0ced6238 100644 >>> --- a/block.c >>> +++ b/block.c >>> @@ -2918,13 +2918,14 @@ BdrvChild >>> *bdrv_root_attach_child(BlockDriverState *child_bs, >>>                                      child_role, perm, shared_perm, >>> opaque, >>>                                      &child, tran, errp); >>>       if (ret < 0) { >>> -        bdrv_unref(child_bs); >>> -        return NULL; >>> +        assert(child == NULL); >>> +        goto out; >>>       } >>>       ret = bdrv_refresh_perms(child_bs, errp); >>> -    tran_finalize(tran, ret); >>> +out: >>> +    tran_finalize(tran, ret); >>>       bdrv_unref(child_bs); >>>       return child; >> >> Looks OK, so: >> >> Reviewed-by: Max Reitz >> >> However, the function’s description says that it will return NULL on >> error.  But if bdrv_refresh_perms() fails, it will still return a >> non-NULL child.  Is that right? >> > > No, it's reset to NULL on transaction abort, so code is correct. It's > not obvious, and I've added a comment and assertion in my version of > this fix "[PATCH 1/6] block: fix leak of tran in bdrv_root_attach_child" The fact that the transaction keeps the pointer to this local variable around is a bit horrifying, but well. Max