From patchwork Tue Oct 27 13:51:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 311968 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 98652C388F9 for ; Tue, 27 Oct 2020 17:37:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F5FA206B2 for ; Tue, 27 Oct 2020 17:37:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603820254; bh=t9MUxy/rvnVfzKKnd3MZ5V2Z0P31u7O5/ODZCAwCwuY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=DEch9+wgjo2vhzQM2sY/CAru31hUJg88ZtD/6xu3d0z7AcDwVUC+3IAypczsqHNZz fT/IPc9ZHV5zR+YY0gBcSnwY9zAQ3OxesWIX1dMD8MAEsa0TktpzaHWzLqFAEWmX2F wEDKWxtWD+8XvIpKuSrg4LJOa3lcxOPPOM3dnLEc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1820707AbgJ0RhZ (ORCPT ); Tue, 27 Oct 2020 13:37:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:34336 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760632AbgJ0Off (ORCPT ); Tue, 27 Oct 2020 10:35:35 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9239522202; Tue, 27 Oct 2020 14:35:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603809335; bh=t9MUxy/rvnVfzKKnd3MZ5V2Z0P31u7O5/ODZCAwCwuY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jkqKPEH9MWiMDVDOgVdZslfD5TpKOAgZRMKEWNUI5nF9YDq1Ah/Q2DbojOIlcBHk3 60CW+EyfywMPkqvUb4heaIUpxF1m53U+9awvfX0FVLMyphQH2Nzk0sl5cxcaY6kaLI miYWdQ+2FFx6TVGpkpSBFu5rnf3kd3pLD3L4r/Lo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vladimir Murzin , Andy Shevchenko , Peter Ujfalusi , Vinod Koul , Sasha Levin Subject: [PATCH 5.4 160/408] dmaengine: dmatest: Check list for emptiness before access its last entry Date: Tue, 27 Oct 2020 14:51:38 +0100 Message-Id: <20201027135502.516950261@linuxfoundation.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201027135455.027547757@linuxfoundation.org> References: <20201027135455.027547757@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Andy Shevchenko [ Upstream commit b28de385b71abf31ce68ec0387638bee26ae9024 ] After writing a garbage to the channel we get an Oops in dmatest_chan_set() due to access to last entry in the empty list. [ 212.670672] BUG: unable to handle page fault for address: fffffff000000020 [ 212.677562] #PF: supervisor read access in kernel mode [ 212.682702] #PF: error_code(0x0000) - not-present page ... [ 212.710074] RIP: 0010:dmatest_chan_set+0x149/0x2d0 [dmatest] [ 212.715739] Code: e8 cc f9 ff ff 48 8b 1d 0d 55 00 00 48 83 7b 10 00 0f 84 63 01 00 00 48 c7 c7 d0 65 4d c0 e8 ee 4a f5 e1 48 89 c6 48 8b 43 10 <48> 8b 40 20 48 8b 78 58 48 85 ff 0f 84 f5 00 00 00 e8 b1 41 f5 e1 Fix this by checking list for emptiness before accessing its last entry. Fixes: d53513d5dc28 ("dmaengine: dmatest: Add support for multi channel testing") Cc: Vladimir Murzin Signed-off-by: Andy Shevchenko Tested-by: Peter Ujfalusi Link: https://lore.kernel.org/r/20200922115847.30100-2-andriy.shevchenko@linux.intel.com Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin --- drivers/dma/dmatest.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c index 62d9825a49e9d..238936e2dfe2d 100644 --- a/drivers/dma/dmatest.c +++ b/drivers/dma/dmatest.c @@ -1218,15 +1218,14 @@ static int dmatest_chan_set(const char *val, const struct kernel_param *kp) add_threaded_test(info); /* Check if channel was added successfully */ - dtc = list_last_entry(&info->channels, struct dmatest_chan, node); - - if (dtc->chan) { + if (!list_empty(&info->channels)) { /* * if new channel was not successfully added, revert the * "test_channel" string to the name of the last successfully * added channel. exception for when users issues empty string * to channel parameter. */ + dtc = list_last_entry(&info->channels, struct dmatest_chan, node); if ((strcmp(dma_chan_name(dtc->chan), strim(test_channel)) != 0) && (strcmp("", strim(test_channel)) != 0)) { ret = -EINVAL;