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 BEFF1C77B73 for ; Tue, 2 May 2023 10:19:52 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ptn67-0004n3-9y; Tue, 02 May 2023 06:19:03 -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 1ptn65-0004lV-7O for qemu-devel@nongnu.org; Tue, 02 May 2023 06:19:01 -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 1ptn63-0000L5-6U for qemu-devel@nongnu.org; Tue, 02 May 2023 06:19:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1683022738; 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=31b0d8QLBF0vY+1zakSA7/awSDWXgOMapmyXoEDqdwA=; b=iwQ6K+eI550IDUxflkBSBkaV8ZBk7dbFwBVJiUeTRZYzqmIilfE4ZnKz/9rgFGy5A0ajlt ls63TBXhwbnv3ZUb1ItcOOooWFjLpZrZLjahxcThTKvlb0MRKPQn+wUEjai7GkYSCUCkUx tiV3f0oPt6mZlUgdU22T6JWHDTp1B5A= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-647-AAR9oWqgPRSsxM-yow34OQ-1; Tue, 02 May 2023 06:18:55 -0400 X-MC-Unique: AAR9oWqgPRSsxM-yow34OQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E06A029AB3EA; Tue, 2 May 2023 10:18:54 +0000 (UTC) Received: from thuth.com (unknown [10.39.193.34]) by smtp.corp.redhat.com (Postfix) with ESMTP id 33251C15BAD; Tue, 2 May 2023 10:18:54 +0000 (UTC) From: Thomas Huth To: qemu-devel@nongnu.org, Richard Henderson Cc: Alexander Bulekov Subject: [PULL 3/3] async: avoid use-after-free on re-entrancy guard Date: Tue, 2 May 2023 12:18:49 +0200 Message-Id: <20230502101849.1655453-4-thuth@redhat.com> In-Reply-To: <20230502101849.1655453-1-thuth@redhat.com> References: <20230502101849.1655453-1-thuth@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.129.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.171, 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_H2=-0.001, 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.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 --- util/async.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) 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; } } -- 2.31.1