From patchwork Tue Mar 4 08:01:51 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: gerben@altlinux.org X-Patchwork-Id: 14000145 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 AD426C021B8 for ; Tue, 4 Mar 2025 08:02:35 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tpNES-00046o-ML; Tue, 04 Mar 2025 03:02:29 -0500 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 1tpNEM-0003yX-4F for qemu-devel@nongnu.org; Tue, 04 Mar 2025 03:02:25 -0500 Received: from air.basealt.ru ([193.43.8.18]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tpNEJ-0003mV-Ju for qemu-devel@nongnu.org; Tue, 04 Mar 2025 03:02:21 -0500 Received: from boringlust.malta.altlinux.ru (obninsk.basealt.ru [217.15.195.17]) (Authenticated sender: rastyoginds) by air.basealt.ru (Postfix) with ESMTPSA id 296B7233B4; Tue, 4 Mar 2025 11:02:16 +0300 (MSK) From: gerben@altlinux.org To: qemu-devel@nongnu.org, kwolf@redhat.com, hreitz@redhat.com Cc: sdl.qemu@linuxtesting.org Subject: [PATCH] block/snapshot: fix *errp handling in bdrv_snapshot_goto Date: Tue, 4 Mar 2025 11:01:51 +0300 Message-ID: <20250304080213.36099-1-gerben@altlinux.org> X-Mailer: git-send-email 2.42.2 MIME-Version: 1.0 Received-SPF: pass client-ip=193.43.8.18; envelope-from=gerben@altlinux.org; helo=air.basealt.ru X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, 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: Denis Rastyogin This error was discovered by fuzzing qemu-img. If bdrv_snapshot_goto() returns an error, it is not handled immediately, allowing *errp to be reassigned when qcow_open() fails, which triggers assert(*errp == NULL) in util/error.c: void error_setv(). This patch ensures that errors from bdrv_snapshot_goto() are handled immediately after the call, preventing *errp from being modified twice and avoiding unnecessary assertion failures. Closes: https://gitlab.com/qemu-project/qemu/-/issues/2851 Signed-off-by: Denis Rastyogin --- block/snapshot.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/block/snapshot.c b/block/snapshot.c index 9c44780e96..d1b5a8d33d 100644 --- a/block/snapshot.c +++ b/block/snapshot.c @@ -296,14 +296,20 @@ int bdrv_snapshot_goto(BlockDriverState *bs, bdrv_graph_wrunlock(); ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp); + if (ret < 0) { + bdrv_unref(fallback_bs); + bs->drv = NULL; + /* A bdrv_snapshot_goto() error takes precedence */ + error_propagate(errp, local_err); + return ret; + } open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err); qobject_unref(options); if (open_ret < 0) { bdrv_unref(fallback_bs); bs->drv = NULL; - /* A bdrv_snapshot_goto() error takes precedence */ error_propagate(errp, local_err); - return ret < 0 ? ret : open_ret; + return open_ret; } /*