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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1A77C43603 for ; Tue, 17 Dec 2019 11:56:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B32062082E for ; Tue, 17 Dec 2019 11:56:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727039AbfLQL4C (ORCPT ); Tue, 17 Dec 2019 06:56:02 -0500 Received: from mga02.intel.com ([134.134.136.20]:53797 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727384AbfLQLz4 (ORCPT ); Tue, 17 Dec 2019 06:55:56 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Dec 2019 03:55:56 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,325,1571727600"; d="scan'208";a="205451607" Received: from black.fi.intel.com (HELO black.fi.intel.com.) ([10.237.72.28]) by orsmga007.jf.intel.com with ESMTP; 17 Dec 2019 03:55:54 -0800 From: Alexander Shishkin To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Alexander Shishkin , Andy Shevchenko , Ammy Yi , stable@vger.kernel.org Subject: [GIT PULL 4/4] intel_th: msu: Fix window switching without windows Date: Tue, 17 Dec 2019 13:55:27 +0200 Message-Id: <20191217115527.74383-5-alexander.shishkin@linux.intel.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191217115527.74383-1-alexander.shishkin@linux.intel.com> References: <20191217115527.74383-1-alexander.shishkin@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 6cac7866c2741 ("intel_th: msu: Add a sysfs attribute to trigger window switch") adds a NULL pointer dereference in the case when there are no windows allocated: > BUG: kernel NULL pointer dereference, address: 0000000000000000 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 1 SMP > CPU: 5 PID: 1110 Comm: bash Not tainted 5.5.0-rc1+ #1 > RIP: 0010:msc_win_switch+0xa/0x80 [intel_th_msu] > Call Trace: > ? win_switch_store+0x9b/0xc0 [intel_th_msu] > dev_attr_store+0x17/0x30 > sysfs_kf_write+0x3e/0x50 > kernfs_fop_write+0xda/0x1b0 > __vfs_write+0x1b/0x40 > vfs_write+0xb9/0x1a0 > ksys_write+0x67/0xe0 > __x64_sys_write+0x1a/0x20 > do_syscall_64+0x57/0x1d0 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix that by disallowing window switching with multiwindow buffers without windows. Signed-off-by: Alexander Shishkin Fixes: 6cac7866c2741 ("intel_th: msu: Add a sysfs attribute to trigger window switch") Reviewed-by: Andy Shevchenko Reported-by: Ammy Yi Tested-by: Ammy Yi Cc: stable@vger.kernel.org # v5.2+ --- drivers/hwtracing/intel_th/msu.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c index 6d240dfae9d9..8e48c7458aa3 100644 --- a/drivers/hwtracing/intel_th/msu.c +++ b/drivers/hwtracing/intel_th/msu.c @@ -1676,10 +1676,13 @@ static int intel_th_msc_init(struct msc *msc) return 0; } -static void msc_win_switch(struct msc *msc) +static int msc_win_switch(struct msc *msc) { struct msc_window *first; + if (list_empty(&msc->win_list)) + return -EINVAL; + first = list_first_entry(&msc->win_list, struct msc_window, entry); if (msc_is_last_win(msc->cur_win)) @@ -1691,6 +1694,8 @@ static void msc_win_switch(struct msc *msc) msc->base_addr = msc_win_base_dma(msc->cur_win); intel_th_trace_switch(msc->thdev); + + return 0; } /** @@ -2025,16 +2030,15 @@ win_switch_store(struct device *dev, struct device_attribute *attr, if (val != 1) return -EINVAL; + ret = -EINVAL; mutex_lock(&msc->buf_mutex); /* * Window switch can only happen in the "multi" mode. * If a external buffer is engaged, they have the full * control over window switching. */ - if (msc->mode != MSC_MODE_MULTI || msc->mbuf) - ret = -ENOTSUPP; - else - msc_win_switch(msc); + if (msc->mode == MSC_MODE_MULTI && !msc->mbuf) + ret = msc_win_switch(msc); mutex_unlock(&msc->buf_mutex); return ret ? ret : size; -- 2.24.0