From patchwork Wed Sep 13 13:17:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 1833547 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=patchwork.ozlabs.org) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4Rm1Nv4Dhlz1yh0 for ; Wed, 13 Sep 2023 23:23:27 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qgPl4-0007AQ-1E; Wed, 13 Sep 2023 09:18:18 -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 1qgPky-00077c-ML; Wed, 13 Sep 2023 09:18:12 -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 1qgPkw-0002pK-06; Wed, 13 Sep 2023 09:18:12 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 4C03B2175D; Wed, 13 Sep 2023 16:18:07 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id 3D39D27C80; Wed, 13 Sep 2023 16:18:01 +0300 (MSK) Received: (nullmailer pid 4073274 invoked by uid 1000); Wed, 13 Sep 2023 13:18:00 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Alexander Bulekov , Thomas Huth , Michael Tokarev Subject: [Stable-8.0.5 03/66] async: avoid use-after-free on re-entrancy guard Date: Wed, 13 Sep 2023 16:17:27 +0300 Message-Id: <20230913131757.4073200-3-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.2 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, 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Alexander Bulekov A BH callback can free the BH, causing a use-after-free in aio_bh_call. Fix that by keeping a local copy of the re-entrancy guard pointer. Buglink: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=58513 Fixes: 9c86c97f12 ("async: Add an optional reentrancy guard to the BH API") Signed-off-by: Alexander Bulekov Message-Id: <20230501141956.3444868-1-alxndr@bu.edu> Reviewed-by: Thomas Huth Signed-off-by: Thomas Huth (cherry picked from commit 7915bd06f25e1803778081161bf6fa10c42dc7cd) Signed-off-by: Michael Tokarev diff --git a/util/async.c b/util/async.c index 9df7674b4e..055070ffbd 100644 --- a/util/async.c +++ b/util/async.c @@ -156,18 +156,20 @@ void aio_bh_call(QEMUBH *bh) { bool last_engaged_in_io = false; - if (bh->reentrancy_guard) { - last_engaged_in_io = bh->reentrancy_guard->engaged_in_io; - if (bh->reentrancy_guard->engaged_in_io) { + /* Make a copy of the guard-pointer as cb may free the bh */ + MemReentrancyGuard *reentrancy_guard = bh->reentrancy_guard; + if (reentrancy_guard) { + last_engaged_in_io = reentrancy_guard->engaged_in_io; + if (reentrancy_guard->engaged_in_io) { trace_reentrant_aio(bh->ctx, bh->name); } - bh->reentrancy_guard->engaged_in_io = true; + reentrancy_guard->engaged_in_io = true; } bh->cb(bh->opaque); - if (bh->reentrancy_guard) { - bh->reentrancy_guard->engaged_in_io = last_engaged_in_io; + if (reentrancy_guard) { + reentrancy_guard->engaged_in_io = last_engaged_in_io; } }