From nobody Tue Nov 26 10:36:11 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1708503873402404.3448132185132; Wed, 21 Feb 2024 00:24:33 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rchqr-00013S-39; Wed, 21 Feb 2024 03:21:13 -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 1rchql-00012A-6g; Wed, 21 Feb 2024 03:21:07 -0500 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 1rchqi-000292-W4; Wed, 21 Feb 2024 03:21:06 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 039234F3C0; Wed, 21 Feb 2024 11:21:20 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id C3D018609F; Wed, 21 Feb 2024 11:20:58 +0300 (MSK) Received: (nullmailer pid 2141992 invoked by uid 1000); Wed, 21 Feb 2024 08:20:58 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Fabiano Rosas , Peter Xu , Michael Tokarev Subject: [Stable-8.2.2 02/60] migration: Fix use-after-free of migration state object Date: Wed, 21 Feb 2024 11:19:50 +0300 Message-Id: <20240221082058.2141850-2-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; 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, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1708503875526100003 Content-Type: text/plain; charset="utf-8" From: Fabiano Rosas We're currently allowing the process_incoming_migration_bh bottom-half to run without holding a reference to the 'current_migration' object, which leads to a segmentation fault if the BH is still live after migration_shutdown() has dropped the last reference to current_migration. In my system the bug manifests as migrate_multifd() returning true when it shouldn't and multifd_load_shutdown() calling multifd_recv_terminate_threads() which crashes due to an uninitialized multifd_recv_state. Fix the issue by holding a reference to the object when scheduling the BH and dropping it before returning from the BH. The same is already done for the cleanup_bh at migrate_fd_cleanup_schedule(). Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1969 Signed-off-by: Fabiano Rosas Link: https://lore.kernel.org/r/20240119233922.32588-2-farosas@suse.de Signed-off-by: Peter Xu (cherry picked from commit 27eb8499edb2bc952c29ddae0bdac9fc959bf7b1) Signed-off-by: Michael Tokarev diff --git a/migration/migration.c b/migration/migration.c index 3ce04b2aaf..ee5e0ba97a 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -650,6 +650,7 @@ static void process_incoming_migration_bh(void *opaque) MIGRATION_STATUS_COMPLETED); qemu_bh_delete(mis->bh); migration_incoming_state_destroy(); + object_unref(OBJECT(migrate_get_current())); } =20 static void coroutine_fn @@ -708,6 +709,7 @@ process_incoming_migration_co(void *opaque) } =20 mis->bh =3D qemu_bh_new(process_incoming_migration_bh, mis); + object_ref(OBJECT(migrate_get_current())); qemu_bh_schedule(mis->bh); return; fail: --=20 2.39.2