From patchwork Sat Mar 15 09:14:37 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 14017892 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 C7AF6C28B28 for ; Sat, 15 Mar 2025 09:21:52 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ttNfO-0007CH-DV; Sat, 15 Mar 2025 05:18:50 -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 1ttNdi-0004Uy-Fz; Sat, 15 Mar 2025 05:17:12 -0400 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ttNdc-00088W-0d; Sat, 15 Mar 2025 05:17:05 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 125FBFFBCB; Sat, 15 Mar 2025 12:13:46 +0300 (MSK) Received: from gandalf.tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with ESMTP id 1AC041CAD64; Sat, 15 Mar 2025 12:14:40 +0300 (MSK) Received: by gandalf.tls.msk.ru (Postfix, from userid 1000) id D1A9C55A5E; Sat, 15 Mar 2025 12:14:39 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Kevin Wolf , Denis Rastyogin , Michael Tokarev Subject: [Stable-7.2.17 26/27] block: Zero block driver state before reopening Date: Sat, 15 Mar 2025 12:14:37 +0300 Message-Id: <20250315091439.657371-26-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.5 In-Reply-To: References: MIME-Version: 1.0 Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, 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 From: Kevin Wolf 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 (cherry picked from commit b75c5f9879166b86ed7c48b772fdcd0693e8a9a3) Signed-off-by: Michael Tokarev diff --git a/block/snapshot.c b/block/snapshot.c index 86e29ca59f..2f6c35f7eb 100644 --- a/block/snapshot.c +++ b/block/snapshot.c @@ -286,6 +286,7 @@ int bdrv_snapshot_goto(BlockDriverState *bs, bdrv_unref_child(bs, fallback); 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) {