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 6BE6AC28B2F for ; Tue, 11 Mar 2025 16:05:25 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ts25p-00086u-TP; Tue, 11 Mar 2025 12:04:35 -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 1ts221-0003vt-I3 for qemu-devel@nongnu.org; Tue, 11 Mar 2025 12:00:37 -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 1ts21z-0005g5-C7 for qemu-devel@nongnu.org; Tue, 11 Mar 2025 12:00:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741708834; 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: in-reply-to:in-reply-to:references:references; bh=5mO5SRVvROBnmvlo4dK2r1R6mGY6qiEPIuhViqul6cM=; b=eQsccjpsiD/GSAe+C8ZRucL4+TjMLb2XBi0XX/J4pdpH9Q0iazhB0yMu8apxV/zxF20hHg 9HSU2dtE+OrHHrvN0cG3KoB0uX7mmS0oEFi+vCqEIoD9nVnJgYYbm0GgVqlujny39Qqm+4 lYyYMJe3cM3MLJYW38nh7Z6zTK46I9I= Received: from mx-prod-mc-02.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-577-0BWuWzDONlquJIdGSx_jBg-1; Tue, 11 Mar 2025 12:00:30 -0400 X-MC-Unique: 0BWuWzDONlquJIdGSx_jBg-1 X-Mimecast-MFC-AGG-ID: 0BWuWzDONlquJIdGSx_jBg_1741708830 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2802A19560A1; Tue, 11 Mar 2025 16:00:30 +0000 (UTC) Received: from merkur.redhat.com (unknown [10.44.33.18]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 83E42180AF7C; Tue, 11 Mar 2025 16:00:28 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, stefanha@redhat.com, qemu-devel@nongnu.org Subject: [PULL 02/22] block: Zero block driver state before reopening Date: Tue, 11 Mar 2025 17:00:01 +0100 Message-ID: <20250311160021.349761-3-kwolf@redhat.com> In-Reply-To: <20250311160021.349761-1-kwolf@redhat.com> References: <20250311160021.349761-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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: -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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=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: 2.1.29 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 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 Closes: https://gitlab.com/qemu-project/qemu/-/issues/2853 Closes: https://gitlab.com/qemu-project/qemu/-/issues/2851 Reported-by: Denis Rastyogin Signed-off-by: Kevin Wolf Message-ID: <20250310104858.28221-1-kwolf@redhat.com> Signed-off-by: Kevin Wolf --- block/snapshot.c | 1 + 1 file changed, 1 insertion(+) diff --git a/block/snapshot.c b/block/snapshot.c index 9c44780e96..22567f1fb9 100644 --- a/block/snapshot.c +++ b/block/snapshot.c @@ -296,6 +296,7 @@ int bdrv_snapshot_goto(BlockDriverState *bs, bdrv_graph_wrunlock(); ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp); + memset(bs->opaque, 0, drv->instance_size); open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err); qobject_unref(options); if (open_ret < 0) { -- 2.48.1