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 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 29D64C282DE for ; Mon, 10 Mar 2025 11:19:41 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1trb9h-0002Yf-Pa; Mon, 10 Mar 2025 07:18:45 -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 1trb9f-0002Xr-GT for qemu-devel@nongnu.org; Mon, 10 Mar 2025 07:18:44 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1trb9d-000291-Mr for qemu-devel@nongnu.org; Mon, 10 Mar 2025 07:18:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741605520; 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=d2ejXY0uHxwizPlTbC+Cj00POKsRg/Z71NBWJFwSfBY=; b=hU/KJkAPj5TWVrF0vyBsjDW5YO80qTdXs/cxMHrhdUhxhLwftRaJc6FuHOhMBqEk+7cq+l kL+QsRlmJbD8h3tDMN2gbTQNEBx9PsyxqHrwjdmReXNr2hFjO/tVMQlTqzgLI29XDk2Nsx Ox/hYaHOI6EDeYUrb/iGRRJ3/UVRM78= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-486-BOoqN2R1M3CqwnAWD5gZIQ-1; Mon, 10 Mar 2025 07:18:34 -0400 X-MC-Unique: BOoqN2R1M3CqwnAWD5gZIQ-1 X-Mimecast-MFC-AGG-ID: BOoqN2R1M3CqwnAWD5gZIQ_1741605513 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C709A19560B4; Mon, 10 Mar 2025 11:18:32 +0000 (UTC) Received: from redhat.com (unknown [10.45.225.222]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3B8071800945; Mon, 10 Mar 2025 11:18:30 +0000 (UTC) Date: Mon, 10 Mar 2025 12:18:27 +0100 From: Kevin Wolf To: qemu-block@nongnu.org Cc: gerben@altlinux.org, qemu-stable@nongnu.org, qemu-devel@nongnu.org Subject: Re: [PATCH] block: Zero block driver state before reopening Message-ID: References: <20250310104858.28221-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250310104858.28221-1-kwolf@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=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: 2.1.29 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 Am 10.03.2025 um 11:48 hat Kevin Wolf geschrieben: > Block drivers assume in their .bdrv_open() implementation that their > state in bs->opaque has been zeroed; it is initially allocated with > g_malloc0() in bdrv_open_driver(). > > bdrv_snapshot_goto() needs to make sure that it is zeroed again before > calling drv->bdrv_open() to avoid that block drivers use stale values. > > One symptom of this bug is VMDK running into a double free when the user > tries to apply an internal snapshot like 'qemu-img snapshot -a test > test.vmdk'. This should be a graceful error because VMDK doesn't support > internal snapshots. > > ==25507== Invalid free() / delete / delete[] / realloc() > ==25507== at 0x484B347: realloc (vg_replace_malloc.c:1801) > ==25507== by 0x54B592A: g_realloc (gmem.c:171) > ==25507== by 0x1B221D: vmdk_add_extent (../block/vmdk.c:570) > ==25507== by 0x1B1084: vmdk_open_sparse (../block/vmdk.c:1059) > ==25507== by 0x1AF3D8: vmdk_open (../block/vmdk.c:1371) > ==25507== by 0x1A2AE0: bdrv_snapshot_goto (../block/snapshot.c:299) > ==25507== by 0x205C77: img_snapshot (../qemu-img.c:3500) > ==25507== by 0x58FA087: (below main) (libc_start_call_main.h:58) > ==25507== Address 0x832f3e0 is 0 bytes inside a block of size 272 free'd > ==25507== at 0x4846B83: free (vg_replace_malloc.c:989) > ==25507== by 0x54AEAC4: g_free (gmem.c:208) > ==25507== by 0x1AF629: vmdk_close (../block/vmdk.c:2889) > ==25507== by 0x1A2A9C: bdrv_snapshot_goto (../block/snapshot.c:290) > ==25507== by 0x205C77: img_snapshot (../qemu-img.c:3500) > ==25507== by 0x58FA087: (below main) (libc_start_call_main.h:58) > > This error was discovered by fuzzing qemu-img. > > Cc: qemu-stable@nongnu.org > Reported-by: Denis Rastyogin > Signed-off-by: Kevin Wolf Forgot these two lines, which I'll add while applying: Closes: https://gitlab.com/qemu-project/qemu/-/issues/2853 Closes: https://gitlab.com/qemu-project/qemu/-/issues/2851 Kevin