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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6ECB7C433EF for ; Mon, 21 Feb 2022 09:41:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234401AbiBUJlV (ORCPT ); Mon, 21 Feb 2022 04:41:21 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:36254 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350250AbiBUJec (ORCPT ); Mon, 21 Feb 2022 04:34:32 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 00B982A253; Mon, 21 Feb 2022 01:14:24 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 84B56CE0E88; Mon, 21 Feb 2022 09:14:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 950C0C340E9; Mon, 21 Feb 2022 09:14:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1645434863; bh=Z9AP8sHVGnKeExOiFmw9xaQ/eAc+E0fki+qkJR1RQuw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JYULPMJqdLAA4C5rMSmvRowwO2RpD5z4eqJcr9+E74dT1eqng8lozW1aJTEZV6Z7q WrdEFaQcQ8mk02aWHqsnzVy00niootUE6R+AHwGLm65aYBOXr2N6kf7wMhm+LZxbbL 9Nfz5OCSD2ypZ1BvKfwLSkWUxmk/pdInVQ2Fj59s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stefan Wahren , Padmanabha Srinivasaiah , Sasha Levin Subject: [PATCH 5.15 150/196] staging: vc04_services: Fix RCU dereference check Date: Mon, 21 Feb 2022 09:49:42 +0100 Message-Id: <20220221084935.944664584@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221084930.872957717@linuxfoundation.org> References: <20220221084930.872957717@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Padmanabha Srinivasaiah [ Upstream commit 0cea730cac824edf78ffd3302938ed5fe2b9d50d ] In service_callback path RCU dereferenced pointer struct vchiq_service need to be accessed inside rcu read-critical section. Also userdata/user_service part of vchiq_service is accessed around different synchronization mechanism, getting an extra reference to a pointer keeps sematics simpler and avoids prolonged graceperiod. Accessing vchiq_service with rcu_read_[lock/unlock] fixes below issue. [ 32.201659] ============================= [ 32.201664] WARNING: suspicious RCU usage [ 32.201670] 5.15.11-rt24-v8+ #3 Not tainted [ 32.201680] ----------------------------- [ 32.201685] drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h:529 suspicious rcu_dereference_check() usage! [ 32.201695] [ 32.201695] other info that might help us debug this: [ 32.201695] [ 32.201700] [ 32.201700] rcu_scheduler_active = 2, debug_locks = 1 [ 32.201708] no locks held by vchiq-slot/0/98. [ 32.201715] [ 32.201715] stack backtrace: [ 32.201723] CPU: 1 PID: 98 Comm: vchiq-slot/0 Not tainted 5.15.11-rt24-v8+ #3 [ 32.201733] Hardware name: Raspberry Pi 4 Model B Rev 1.4 (DT) [ 32.201739] Call trace: [ 32.201742] dump_backtrace+0x0/0x1b8 [ 32.201772] show_stack+0x20/0x30 [ 32.201784] dump_stack_lvl+0x8c/0xb8 [ 32.201799] dump_stack+0x18/0x34 [ 32.201808] lockdep_rcu_suspicious+0xe4/0xf8 [ 32.201817] service_callback+0x124/0x400 [ 32.201830] slot_handler_func+0xf60/0x1e20 [ 32.201839] kthread+0x19c/0x1a8 [ 32.201849] ret_from_fork+0x10/0x20 Tested-by: Stefan Wahren Signed-off-by: Padmanabha Srinivasaiah Link: https://lore.kernel.org/r/20211231195406.5479-1-treasure4paddy@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- .../interface/vchiq_arm/vchiq_arm.c | 20 +++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c index 967f10b9582a8..ea9a53bdb4174 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c @@ -1033,15 +1033,27 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header, DEBUG_TRACE(SERVICE_CALLBACK_LINE); + rcu_read_lock(); service = handle_to_service(handle); - if (WARN_ON(!service)) + if (WARN_ON(!service)) { + rcu_read_unlock(); return VCHIQ_SUCCESS; + } user_service = (struct user_service *)service->base.userdata; instance = user_service->instance; - if (!instance || instance->closing) + if (!instance || instance->closing) { + rcu_read_unlock(); return VCHIQ_SUCCESS; + } + + /* + * As hopping around different synchronization mechanism, + * taking an extra reference results in simpler implementation. + */ + vchiq_service_get(service); + rcu_read_unlock(); vchiq_log_trace(vchiq_arm_log_level, "%s - service %lx(%d,%p), reason %d, header %lx, instance %lx, bulk_userdata %lx", @@ -1074,6 +1086,7 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header, NULL, user_service, bulk_userdata); if (status != VCHIQ_SUCCESS) { DEBUG_TRACE(SERVICE_CALLBACK_LINE); + vchiq_service_put(service); return status; } } @@ -1084,11 +1097,13 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header, vchiq_log_info(vchiq_arm_log_level, "%s interrupted", __func__); DEBUG_TRACE(SERVICE_CALLBACK_LINE); + vchiq_service_put(service); return VCHIQ_RETRY; } else if (instance->closing) { vchiq_log_info(vchiq_arm_log_level, "%s closing", __func__); DEBUG_TRACE(SERVICE_CALLBACK_LINE); + vchiq_service_put(service); return VCHIQ_ERROR; } DEBUG_TRACE(SERVICE_CALLBACK_LINE); @@ -1117,6 +1132,7 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header, header = NULL; } DEBUG_TRACE(SERVICE_CALLBACK_LINE); + vchiq_service_put(service); if (skip_completion) return VCHIQ_SUCCESS; -- 2.34.1